0000950170-24-093311 | 10-Q | XBRL Viewer | Amylyx Pharmaceuticals INC

Stock Option and Grant Plan (Tables)

6 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

A summary of option activity for the six months ended June 30, 2024, is as follows:


	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2023		9,823,248		$	18.39		7.9	$	27,639
Granted		3,053,811		$	8.56
Exercised		(109,599	)	$	1.54			$	745
Cancelled or forfeited		(2,025,321	)	$	20.73
Outstanding at June 30, 2024		10,742,139		$	15.33		7.9	$	287
Options exercisable as of June 30, 2024		5,147,314		$	15.72		6.9	$	272
Options unvested as of June 30, 2024		5,594,825		$	14.95		8.9	$	15
Weighted average grant-date fair value of options granted during the period	$	5.62

Summary of Restricted Stock Unit Activity

A summary of restricted stock unit activity for the six months ended June 30, 2024, is as follows:


	Number of Shares			Weighted Average Grant Date Fair Value
Nonvested as of December 31, 2023		1,112,542		$	24.80
Granted		2,816,142		$	8.82
Vested		(263,901	)	$	24.37
Forfeited		(753,883	)	$	20.23
Nonvested as of June 30, 2024		2,910,900		$	10.56

Summary of Stock-Based Compensation Expense

Stock-based compensation expense for the three and six months ended June 30, 2024 and 2023, is as follows (in thousands):


	Three Months Ended June 30,				Six Months Ended June 30,
	2024		2023		2024		2023
Research and development	$	2,449	$	2,535	$	5,161	$	4,426
Selling, general and administrative		7,121		7,415		14,333		13,025
Total stock-based compensation expense	$	9,570	$	9,950	$	19,494	$	17,451

Summary of Unrecognized Stock-Based Compensation Expense and Weighted-Average Recognition Period

The following table summarizes unrecognized stock-based compensation expense as of June 30, 2024, by type of awards (in thousands), and the weighted-average period over which that expense is expected to be recognized (in years). The total unrecognized stock-based compensation expense will be adjusted for actual forfeitures as they occur.


	June 30, 2024
	Unrecognized Expense		Weighted-average Recognition Period
Stock options	$	53,765		2.48
Restricted stock units	$	26,996		2.92

Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2023 and the notes thereto, which are included in the Company’s most recent Annual Report on Form 10-K. Since the date of those consolidated financial statements, there have been no material changes to its significant accounting policies. Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements are unaudited and have been prepared in conformity with accounting principles generally accepted in the U.S., or GAAP, and include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. In the opinion of the Company's management, all normal and recurring adjustments necessary for a fair presentation have been reflected. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the ASC, and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB. Use of Estimates The preparation of the condensed consolidated financial statements in conformity with GAAP requires the Company’s management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amount of expenses during the reporting period. Actual results could differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies in developing the estimates and assumptions that are used in the preparation of the financial statements. Management must apply significant judgment in this process. Management’s estimation process often may yield a range of potentially reasonable estimates and management must select an amount that falls within that range of reasonable estimates. New Accounting Pronouncements Not Yet Adopted In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvement to Income Tax Disclosures, or ASU 2023-09, to enhance the transparency and decision usefulness of income tax disclosures. ASU 2023-09 is effective for annual periods beginning after December 15, 2024, on a prospective basis. Early adoption and retrospective application are permitted. The Company is currently evaluating the impact of this ASU on its consolidated financial statements and related disclosures. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, or ASU 2023-09, which requires public entities to disclose information about their reportable segments’ significant expenses on an interim and annual basis. ASU 2023-07 is effective for the Company beginning the year ended December 31, 2024. The Company is currently evaluating the impact of this ASU on its consolidated financial statements and related disclosures.

Summary of Significant Accounting Policies

6 Months Ended

Jun. 30, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Significant Accounting Policies

The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2023 and the notes thereto, which are included in the Company’s most recent Annual Report on Form 10-K. Since the date of those consolidated financial statements, there have been no material changes to its significant accounting policies.

Basis of Presentation and Consolidation

The accompanying condensed consolidated financial statements are unaudited and have been prepared in conformity with accounting principles generally accepted in the U.S., or GAAP, and include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. In the opinion of the Company's management, all normal and recurring adjustments necessary for a fair presentation have been reflected. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the ASC, and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB.

Use of Estimates

The preparation of the condensed consolidated financial statements in conformity with GAAP requires the Company’s management to make estimates and assumptions that affect the reported amounts of assets and liabilities at the date of the financial statements and the reported amount of expenses during the reporting period. Actual results could differ from those estimates. Management considers many factors in selecting appropriate financial accounting policies in developing the estimates and assumptions that are used in the preparation of the financial statements. Management must apply significant judgment in this process. Management’s estimation process often may yield a range of potentially reasonable estimates and management must select an amount that falls within that range of reasonable estimates.

New Accounting Pronouncements Not Yet Adopted

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvement to Income Tax Disclosures, or ASU 2023-09, to enhance the transparency and decision usefulness of income tax disclosures. ASU 2023-09 is effective for annual periods beginning after December 15, 2024, on a prospective basis. Early adoption and retrospective application are permitted. The Company is currently evaluating the impact of this ASU on its consolidated financial statements and related disclosures.

In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures, or ASU 2023-09, which requires public entities to disclose information about their reportable segments’ significant expenses on an interim and annual basis. ASU 2023-07 is effective for the Company beginning the year ended December 31, 2024. The Company is currently evaluating the impact of this ASU on its consolidated financial statements and related disclosures.

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2024	Jul. 31, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Trading Symbol	AMLX
Entity Registrant Name	Amylyx Pharmaceuticals, Inc.
Entity Central Index Key	0001658551
Current Fiscal Year End Date	--12-31
Entity File Number	001-41199
Entity Tax Identification Number	46-4600503
Entity Address, Address Line One	43 Thorndike St.
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02141
City Area Code	617
Local Phone Number	682-0917
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		68,082,468
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Stock Option and Grant Plan - Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Share-Based Payment Arrangement [Abstract]
Aggregate intrinsic value, exercised	$ 745	$ 16,200
Total fair value of stock options vested	$ 23,700	$ 19,900

Stock Option and Grant Plan - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Number of Options, Outstanding	9,823,248
Number of Options, Granted	3,053,811
Number of Options, Exercised	(109,599)
Number of Options, Cancelled or forfeited	(2,025,321)
Number of Options, Outstanding	10,742,139		9,823,248
Number of Options, Options exercisable	5,147,314
Number of Options, Options unvested	5,594,825
Weighted average grant-date fair value of options granted during the period	$ 5.62
Weighted-Average Exercise Price, Outstanding	18.39
Weighted-Average Exercise Price, Granted	8.56
Weighted-Average Exercise Price, Exercised	1.54
Weighted-Average Exercise Price, Cancelled or forfeited	20.73
Weighted-Average Exercise Price, Outstanding	15.33		$ 18.39
Weighted-Average Exercise Price, Options exercisable	15.72
Weighted-Average Exercise Price, Options unvested	$ 14.95
Weighted- Average Remaining Contractual Term (in years), Outstanding	7 years 10 months 24 days		7 years 10 months 24 days
Weighted- Average Remaining Contractual Term (in years), Options exercisable	6 years 10 months 24 days
Weighted- Average Remaining Contractual Term (in years), Options unvested	8 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding	$ 27,639
Aggregate intrinsic value, exercised	745	$ 16,200
Aggregate Intrinsic Value, Outstanding	287		$ 27,639
Aggregate Intrinsic Value, Options exercisable	272
Aggregate Intrinsic Value, Options unvested	$ 15

Short-Term Investments

6 Months Ended

Jun. 30, 2024

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

4. SHORT-TERM INVESTMENTS

The Company has classified all of its marketable securities at June 30, 2024 as “available-for-sale”. The Company records available-for-sale securities at fair value, with the unrealized gains and losses included as a separate component of other accumulated comprehensive income (loss). There were no realized gains or losses recognized during the three and six months ended June 30, 2024 and 2023.

The Company adjusts the cost of available-for-sale debt securities for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in interest income. The cost of securities sold is based on the specific identification method. The Company includes interest and dividends on securities classified as available-for-sale in interest income. Accrued interest receivable relating to the Company's available-for-sale securities is presented within prepaid expenses and other current assets in the accompanying condensed consolidated balance sheets, and amounted to less than $0.1 million and $0.5 million at June 30, 2024 and December 31, 2023, respectively.

As of June 30, 2024, there were no securities in an unrealized loss position for greater than 12 months. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases. The Company did not record an allowance for credit losses as of June 30, 2024.

Short-term investments, which are classified as available-for-sale, consisted of the following (in thousands):


Balance at June 30, 2024:	Amortized Cost Basis		Unrealized Gain		Unrealized Loss			Fair Value
Treasury bills	$	234,842	$	1	$	(30	)	$	234,813
Total short-term investments	$	234,842	$	1	$	(30	)	$	234,813


Balance at December 31, 2023:	Amortized Cost Basis		Unrealized Gain		Unrealized Loss			Fair Value
Treasury bills	$	196,098	$	67	$	—		$	196,165
U.S. agency bonds		4,999		—		(3	)		4,996
Total short-term investments	$	201,097	$	67	$	(3	)	$	201,161

Fair Value Measurements

6 Months Ended

Jun. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurements

7. FAIR VALUE MEASUREMENTS

The following tables present information about the Company’s financial assets and liabilities measured at fair value on a recurring basis and indicates the level of the fair value hierarchy utilized to determine such fair values (in thousands):


	June 30, 2024
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	536	$	—	$	—	$	536
Short-term investments:
Treasury bills		234,813		—		—		234,813
Total short-term investments		234,813		—		—		234,813
Restricted cash equivalents		719		—		—		719
Total financial assets	$	236,068	$	—	$	—	$	236,068


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	76,710	$	—	$	—	$	76,710
Short-term investments:
Treasury bills		196,165		—		—		196,165
U.S. agency bonds		—		4,996		—		4,996
Total short-term investments		196,165		4,996		—		201,161
Restricted cash equivalents		719		—		—		719
Total financial assets	$	273,594	$	4,996	$	—	$	278,590

The Company classifies its money market funds and treasury bills as Level 1 assets under the fair value hierarchy, as these assets have been valued using quoted market prices for identical assets in active markets without any valuation adjustment. The Company classifies its U.S. agency bonds as Level 2 assets under the fair value hierarchy, as these assets have been valued using information obtained through a third-party pricing service at each balance sheet date, using observable market inputs for similar assets that may include trade information, broker or dealer quotes, bids, offers, or a combination of these data sources.

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued external research and development	$ 7,466	$ 12,625
Accrued benefits and incentive compensation	6,067	16,790
Accrued Manufacturing	9,008	1,652
Accrued consulting and other professional fees	2,424	6,506
Accrued returns, rebates and co-pay assistance	22,059	16,063
Accrued royalties		3,111
Accrued loss on future purchase commitments	12,604
Accrued restructuring expenses	2,648
Other accrued expenses	481	977
Total accrued expenses	$ 62,757	$ 57,724

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	$ 234,813	$ 201,161
Fair Value Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	234,813	201,161
Assets measured at fair value	236,068	278,590
Fair Value Measurements, Recurring \| Cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	536	76,710
Fair Value Measurements, Recurring \| Treasury Bills
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	234,813	196,165
Fair Value Measurements, Recurring \| U.S. Agency Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments		4,996
Fair Value Measurements, Recurring \| Restricted Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	719	719
Fair Value Measurements, Recurring \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	234,813	196,165
Assets measured at fair value	236,068	273,594
Fair Value Measurements, Recurring \| Level 1 \| Cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	536	76,710
Fair Value Measurements, Recurring \| Level 1 \| Treasury Bills
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments	234,813	196,165
Fair Value Measurements, Recurring \| Level 1 \| Restricted Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 719	719
Fair Value Measurements, Recurring \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments		4,996
Assets measured at fair value		4,996
Fair Value Measurements, Recurring \| Level 2 \| U.S. Agency Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments		$ 4,996

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (72,700)	$ (118,793)	$ 22,074	$ 1,573	$ (191,493)	$ 23,647

Short-Term Investments - Additional Information (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) Security	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) Security	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Debt Securities, Available-for-Sale [Line Items]
Realized gains	$ 0	$ 0	$ 0	$ 0
Realized loss	$ 0	$ 0	$ 0	$ 0
Debt securities available-for-sale in an unrealized loss position for greater than 12 months \| Security	0		0
Available-for-Sale Securities \| Maximum
Debt Securities, Available-for-Sale [Line Items]
Accrued interest receivable	$ 100,000		$ 100,000		$ 500,000

Stock Option and Grant Plan - Summary of Restricted Stock Unit Activity (Details) - Restricted Stock Unit	6 Months Ended
	Jun. 30, 2024 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, Nonvested \| shares	1,112,542
Number of shares, Granted \| shares	2,816,142
Number of shares, Vested \| shares	(263,901)
Number of shares, Forfeited \| shares	(753,883)
Number of shares, Nonvested \| shares	2,910,900
Weighted Average Grant Date Fair Value, Nonvested \| $ / shares	$ 24.8
Weighted Average Grant Date Fair Value, Granted \| $ / shares	8.82
Weighted Average Grant Date Fair Value, Vested \| $ / shares	24.37
Weighted Average Grant Date Fair Value, Forfeited \| $ / shares	20.23
Weighted Average Grant Date Fair Value, Nonvested \| $ / shares	$ 10.56

Inventories - Summary of Inventory (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Inventory Disclosure [Abstract]
Raw materials	$ 53,144
Work in process	18,945
Finished goods	11,191
Total inventories	$ 83,280

Subsequent Events - Additional Information (Details) - Subsequent Event - Eiger BioPharmaceuticals, Inc. $ in Millions	Jul. 09, 2024 USD ($)
Subsequent Event [Line Items]
Transaction costs	$ 35.1
Maximum
Subsequent Event [Line Items]
Percentage of royalty obligations on future sales	7.00%
Minimum
Subsequent Event [Line Items]
Percentage of royalty obligations on future sales	4.00%

Restructuring - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended
	Apr. 30, 2024	Jun. 30, 2024
Restructuring Cost and Reserve [Line Items]
Accrued restructuring expenses		$ 2,648
Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Percentage of reduction in workforce	70.00%
Impairment of capitalized internal-use software		900
Accrued restructuring expenses		$ 2,600

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning Balance, Shares at Dec. 31, 2022		66,512,011
Beginning Balance at Dec. 31, 2022	$ 340,607	$ 7	$ 694,906	$ (86)	$ (354,220)
Issuance of common stock upon exercise of stock options, Shares		451,298
Issuance of common stock upon exercise of stock options	2,777		2,777
Issuance of common stock upon vesting of RSUs		132,294
Stock-based compensation expense	7,580		7,580
Other comprehensive loss	111			111
Net (loss) income	1,573				1,573
Ending Balance, Shares at Mar. 31, 2023		67,095,603
Ending Balance at Mar. 31, 2023	352,648	$ 7	705,263	25	(352,647)
Beginning Balance, Shares at Dec. 31, 2022		66,512,011
Beginning Balance at Dec. 31, 2022	340,607	$ 7	694,906	(86)	(354,220)
Net (loss) income	23,647
Ending Balance, Shares at Jun. 30, 2023		67,354,417
Ending Balance at Jun. 30, 2023	386,365	$ 7	717,003	(72)	(330,573)
Beginning Balance, Shares at Mar. 31, 2023		67,095,603
Beginning Balance at Mar. 31, 2023	352,648	$ 7	705,263	25	(352,647)
Issuance of common stock upon exercise of stock options, Shares		226,138
Issuance of common stock upon exercise of stock options	1,687		1,687
Issuance of common stock upon vesting of RSUs		32,676
Stock-based compensation expense	10,053		10,053
Other comprehensive loss	(97)			(97)
Net (loss) income	22,074				22,074
Ending Balance, Shares at Jun. 30, 2023		67,354,417
Ending Balance at Jun. 30, 2023	$ 386,365	$ 7	717,003	(72)	(330,573)
Beginning Balance, Shares at Dec. 31, 2023	67,707,432	67,707,432
Beginning Balance at Dec. 31, 2023	$ 433,432	$ 7	738,177	197	(304,949)
Issuance of common stock upon exercise of stock options, Shares		49,618
Issuance of common stock upon exercise of stock options	147		147
Issuance of common stock upon vesting of RSUs		218,537
Stock-based compensation expense	9,924		9,924
Other comprehensive loss	(274)			(274)
Net (loss) income	(118,793)				(118,793)
Ending Balance, Shares at Mar. 31, 2024		67,975,587
Ending Balance at Mar. 31, 2024	$ 324,436	$ 7	748,248	(77)	(423,742)
Beginning Balance, Shares at Dec. 31, 2023	67,707,432	67,707,432
Beginning Balance at Dec. 31, 2023	$ 433,432	$ 7	738,177	197	(304,949)
Issuance of common stock upon exercise of stock options, Shares	109,599
Net (loss) income	$ (191,493)
Ending Balance, Shares at Jun. 30, 2024	68,079,057	68,079,057
Ending Balance at Jun. 30, 2024	$ 261,309	$ 7	757,841	(97)	(496,442)
Beginning Balance, Shares at Mar. 31, 2024		67,975,587
Beginning Balance at Mar. 31, 2024	324,436	$ 7	748,248	(77)	(423,742)
Issuance of common stock upon exercise of stock options, Shares		59,981
Issuance of common stock upon exercise of stock options	23		23
Issuance of common stock upon vesting of RSUs		43,489
Stock-based compensation expense	9,570		9,570
Other comprehensive loss	(20)			(20)
Net (loss) income	$ (72,700)				(72,700)
Ending Balance, Shares at Jun. 30, 2024	68,079,057	68,079,057
Ending Balance at Jun. 30, 2024	$ 261,309	$ 7	$ 757,841	$ (97)	$ (496,442)

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred stock par value	$ 0.0001	$ 0.0001
Preferred stock shares authorized	10,000,000	10,000,000
Common stock, stated par value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares, issued	68,079,057	67,707,432
Common stock, shares, outstanding	68,079,057	67,707,432

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 74,999	$ 170,201
Short-term investments	234,813	201,161
Accounts receivable, net	4,091	40,050
Inventories		38,323
Prepaid expenses and other current assets	12,819	14,931
Total current assets	326,722	464,666
Property and equipment, net	1,473	2,686
Restricted cash equivalents	719	719
Operating lease right-of-use assets	2,769	3,725
Long-term inventories		44,957
Other assets	479	701
Total assets	332,162	517,454
Current liabilities:
Accounts payable	4,955	22,061
Accrued expenses	62,757	57,724
Operating lease liabilities, current portion	2,369	2,257
Total current liabilities	70,081	82,042
Operating lease liabilities, net of current portion	772	1,980
Total liabilities	70,853	84,022
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized
Common stock, $0.0001 par value; 300,000,000 shares authorized; 68,079,057 and 67,707,432 shares issued and outstanding as of June 30, 2024 and December 31, 2023, respectively	7	7
Additional paid-in capital	757,841	738,177
Accumulated deficit	(496,442)	(304,949)
Accumulated other comprehensive (loss) income	(97)	197
Total stockholders' equity	261,309	433,432
Total liabilities and stockholders' equity	$ 332,162	$ 517,454

Restructuring - Schedule of Restructuring Expenses (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2024
Restructuring and Related Activities [Abstract]
Severance and employee benefit costs	$ 21,812	$ 21,812
Contract termination costs, impairment of assets and other costs	1,039	1,039
Total	$ 22,851	$ 22,851

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Jun. 30, 2024
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During the three months ended June 30, 2024, no officer or director of the Company (as defined in Rule 16a-1(f)) adopted or terminated a “Rule 10b5-1 trading arrangement” or a “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K of the Exchange Act.
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Cash flows (used in) provided by operating activities:
Net (loss) income	$ (191,493)	$ 23,647
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Stock-based compensation expense	19,494	17,451
Depreciation expense	523	485
Accretion of investment discounts, net	(5,760)	(4,886)
Inventory impairment and loss on firm purchase commitments	117,871
Other non-cash items	827
Changes in operating assets and liabilities:
Accounts receivable, net	35,958	(18,167)
Inventories	(9,253)	(32,636)
Interest receivable	421	(356)
Prepaid expenses and other current assets	1,657	(1,318)
Operating lease right-of-use assets	957	881
Other assets	217
Accounts payable	(17,087)	18,455
Accrued expenses	(20,305)	971
Operating lease liabilities	(1,096)	(990)
Net cash (used in) provided by operating activities	(67,069)	3,537
Cash flows (used in) provided by investing activities:
Purchases of property and equipment	(156)	(528)
Purchases of investments	(231,986)	(9,756)
Proceeds from maturities of short-term investments	204,000	189,500
Net cash (used in) provided by investing activities	(28,142)	179,216
Cash flows provided by financing activities:
Follow-on offering costs paid		(136)
Proceeds from exercise of stock options and RSUs vesting	1,493	5,663
Withholding taxes paid on stock-based awards	(1,335)	(3,103)
Net cash provided by financing activities	158	2,424
Effect of exchange rate changes on cash, cash equivalents and restricted cash equivalents	(149)	57
Net (decrease) increase in cash, cash equivalents and restricted cash equivalents	(95,202)	185,234
Cash, cash equivalents and restricted cash equivalents, beginning of period	170,920	63,245
Cash, cash equivalents and restricted cash equivalents, end of period	75,718	248,479
Supplemental disclosure of cash flow information:
Taxes withheld on stock-based awards included in accrued expenses	12	67
Purchases of property and equipment included in accounts payable		81
Income taxes paid	$ 281	$ 2,562

Nature of the Business - Additional Information (Details)	6 Months Ended
	Jun. 30, 2024
Nature Of The Information [Abstract]
Participants dose description	The Company dosed the first participant in the HELIOS trial, a Phase 2 trial of AMX0035 for the treatment of Wolfram syndrome, in April 2023. Amylyx plans to present the HELIOS topline data for all 12 participants at Week 24, including all of the longer-term data available for participants who have reached their Week 36 or Week 48 visit at that time, at a medical meeting this fall. The Company is engaging with stakeholders, including the FDA, and planning for a single Phase 3 clinical trial and will share additional details on the clinical trial design once finalized. The Company dosed the first participant in the ORION trial, a Phase 2b/3 global clinical trial of AMX0035 for the treatment of PSP, in December 2023. Data from an interim analysis of the ORION are expected in mid-2025. The Company is also advancing additional drug candidates developed by Amylyx for neurodegenerative diseases including AMX0114, a potent antisense oligonucleotide targeting inhibition of Calpain-2, a key contributor to the axonal (also known as Wallerian) degeneration pathway. The Company is preparing to initiate a multiple ascending dose clinical trial of AMX0114 in people living with ALS in the second half of 2024.

Inventories - Additional Information (Details) $ in Millions	6 Months Ended
	Jun. 30, 2024 USD ($)
Inventory Disclosure [Abstract]
Inventory write-downs	$ 92.5

Short-Term Investments - Schedule of Short-term Investments Classified as Available-for-sale (Details) - Short-term Investments - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	$ 234,842	$ 201,097
Unrealized Gain	1	67
Unrealized Loss	(30)	(3)
Fair Value	234,813	201,161
Treasury Bills
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	234,842	196,098
Unrealized Gain	1	67
Unrealized Loss	(30)
Fair Value	$ 234,813	196,165
Agency Bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis		4,999
Unrealized Loss		(3)
Fair Value		$ 4,996

Product Revenue, Net - Schedule of Activity and Ending Reserve Balance for GTN Adjustments (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
GTN Adjustments, Ending balance	$ 19,162	$ 4,304
GTN Adjustments, Provision related to sales in the current year	29,403	23,716
GTN Adjustments, Adjustments related to prior period sales	(2,758)	(402)
GTN Adjustments, Credits and payments made	(22,922)	(16,113)
GTN Adjustments, Ending balance	22,885	11,505
Chargebacks and Cash Discounts
Disaggregation of Revenue [Line Items]
GTN Adjustments, Ending balance	3,143	648
GTN Adjustments, Provision related to sales in the current year	4,983	10,053
GTN Adjustments, Adjustments related to prior period sales	(1,696)
GTN Adjustments, Credits and payments made	(6,430)	(5,831)
GTN Adjustments, Ending balance		4,870
Medicaid and Medicare Rebates
Disaggregation of Revenue [Line Items]
GTN Adjustments, Ending balance	4,946	1,992
GTN Adjustments, Provision related to sales in the current year	3,504	6,516
GTN Adjustments, Adjustments related to prior period sales		(236)
GTN Adjustments, Credits and payments made	(7,664)	(4,294)
GTN Adjustments, Ending balance	786	3,978
Other Rebates, Returns, Discounts and Adjustments
Disaggregation of Revenue [Line Items]
GTN Adjustments, Ending balance	11,073	1,664
GTN Adjustments, Provision related to sales in the current year	20,916	7,147
GTN Adjustments, Adjustments related to prior period sales	(1,062)	(166)
GTN Adjustments, Credits and payments made	(8,828)	(5,988)
GTN Adjustments, Ending balance	$ 22,099	$ 2,657