Pay vs Performance Disclosure - USD ($)

12 Months Ended

Dec. 31, 2025

Dec. 31, 2024

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Pay vs Performance Disclosure

Pay vs Performance Disclosure, Table

					VALUE OF INITIAL FIXED $100 INVESTMENT BASED ON:		(IN THOUSANDS)
YEAR	SUMMARY COMPENSATION TABLE TOTAL FOR PEO ($)(1)	COMPENSATION ACTUALLY PAID TO PEO ($)(1)(3)(5)	AVERAGE SUMMARY COMPENSATION TABLE TOTAL FOR NON-PEO NEOS ($)(2)	AVERAGE COMPENSATION ACTUALLY PAID TO NON-PEO NEOS ($)(2)(4)(5)	TSR ($)(6)	PEER GROUP TSR ($)(6)	NET INCOME (LOSS) ($)	CSM - GLOBAL NET PRODUCT REVENUES ($)
2025	14,867,600	77,428,521	6,582,418	19,817,949	305.96	124.75	313,747	2,986,549
2024	11,492,970	29,836,503	3,034,948	7,842,013	181.05	93.49	(278,157)	1,646,228
2023	8,895,670	11,410,294	2,922,458	1,574,481	147.27	94.03	(440,242)	1,241,474
2022	4,588,810	19,043,460	3,580,510	12,601,300	182.85	89.90	(1,131,156)	894,329
2021	10,176,685	17,514,345	5,918,910	10,714,290	130.48	100.02	(852,824)	662,138

Company Selected Measure Name

global net product revenues

Named Executive Officers, Footnote

For 2025, 2024, 2023 and 2022, our PEO was Yvonne L. Greenstreet, M.D. For 2021 our PEO was John M. Maraganore, Ph.D. For 2025 our non-PEO NEOs were Jeffrey V. Poulton, Bryan A. Supran, Pushkal Garg, M.D., and Tolga Tanguler. For 2024, our non-PEO NEOs were Mr. Poulton, Dr. Garg, Mr. Tanguler, and Kevin J. Fitzgerald, Ph.D. For 2023, our non-PEO NEOs were Mr. Poulton, Dr. Garg, Mr. Tanguler, Indrani L. Franchini, and Akshay K. Vaishnaw, M.D., Ph.D. For 2022, our non-PEO NEOs were Dr. Vaishnaw, Mr. Poulton, Dr. Garg, and Ms. Franchini. For 2021, our non-PEO NEOs were Dr. Greenstreet, Dr. Vaishnaw, Mr. Poulton, and Mr. Tanguler.

Peer Group Issuers, Footnote

The company TSR and the company’s Peer Group TSR reflected in these columns for each applicable fiscal year is calculated based on a fixed investment of $100 at the applicable measurement point on the same cumulative basis as is used in Item 201(e) of Regulation S-K. The peer group used to determine the company’s Peer Group TSR for each applicable fiscal year is the following published industry index, as disclosed in our Annual Report on Form 10-K for the year ended December 31, 2025 pursuant to Item 201(e) of Regulation S-K: Nasdaq Biotechnology Index (NBI).

PEO Total Compensation Amount

$ 14,867,600

$ 11,492,970

$ 8,895,670

$ 4,588,810

$ 10,176,685

PEO Actually Paid Compensation Amount

$ 77,428,521

29,836,503

11,410,294

19,043,460

17,514,345

Adjustment To PEO Compensation, Footnote

The following is a summary of the adjustments made to PEO compensation as reported in the Summary Compensation Table to determine PEO CAP as reported in this table:

	2025	2024	2023	2022	2021
Total Compensation Reported in SCT	14,867,600	11,492,970	8,895,670	4,588,810	10,176,685
LESS: the grant date fair value of equity awards granted in the year indicated	(9,875,880)	(7,239,400)	(6,744,150)	(2,498,790)	(7,861,410)
ADD: the year-end fair value of outstanding and unvested equity awards granted in the year indicated(a)	34,291,241	17,187,024	8,173,520	5,823,820	9,100,080
ADD: the change in fair value of equity awards granted in years prior to the year indicated that were outstanding and unvested at the end of the year indicated (as compared to fair value at the end of the immediately prior year)(a)	21,947,941	2,538,755	344,240	7,353,620	2,419,780
ADD: the change in fair value of equity awards granted in years prior to the year indicated that vested in the year indicated (fair value at vesting date as compared to the end of the immediately prior year)(a)	16,197,619	5,857,154	741,014	3,776,000	3,679,210
Total (Net) Adjustments	77,428,521	29,836,503	11,410,294	19,043,460	17,514,345

(a)We determined the year-end fair value of PSUs for the year indicated. If the achievement of the performance condition for the PSU was not probable, as defined under applicable accounting guidance, we assigned a fair value of $0.

Non-PEO NEO Average Total Compensation Amount

$ 6,582,418

3,034,948

2,922,458

3,580,510

5,918,910

Non-PEO NEO Average Compensation Actually Paid Amount

$ 19,817,949

7,842,013

1,574,481

12,601,300

10,714,290

Adjustment to Non-PEO NEO Compensation Footnote

The following is a summary of the adjustments made to average non-PEO NEO compensation as reported in the Summary Compensation Table to determine average non-PEO NEO CAP as reported in this table:

	2025	2024	2023	2022	2021
Average Total Compensation Reported in SCT	6,582,418	3,034,948	2,922,458	3,580,510	5,918,910
LESS: the grant date fair value of equity awards granted in the year indicated	(5,105,633)	(1,688,240)	(1,888,468)	(2,548,800)	(4,891,560)
ADD: the year-end fair value of outstanding and unvested equity awards granted in the year indicated(a)	10,365,563	3,978,386	2,288,708	5,582,350	6,583,990
ADD: the change in fair value of equity awards granted in years prior to the year indicated that were outstanding and unvested at the end of the year indicated (as compared to fair value at the end of the immediately prior year)(a)	4,471,311	1,028,665	(852,294)	3,941,750	962,260
ADD: the change in fair value of equity awards granted in years prior to the year indicated that vested in the year indicated (fair value at vesting date as compared to the end of the immediately prior year)(a)	3,504,290	1,488,254	(895,923)	2,045,490	2,140,690
Total (Net) Adjustments	19,817,949	7,842,013	1,574,481	12,601,300	10,714,290

(a)We determined the year-end fair value of PSUs for the year indicated. If the achievement of the performance condition for the PSU was not probable, as defined under applicable accounting guidance, we assigned a fair value of $0.

Compensation Actually Paid vs. Total Shareholder Return

The following graphs reflect the relationships between (i) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our net income (loss), (ii) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our cumulative total shareholder return and our cumulative total shareholder return to our peer group total shareholder return, and (iii) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our global net product revenues (the CSM), in each case for the years 2021 through 2025.

  PEO CAP   Non-PEO Avg CAP   Alnylam TSR   Peer Group TSR

Compensation Actually Paid vs. Net Income

The following graphs reflect the relationships between (i) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our net income (loss), (ii) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our cumulative total shareholder return and our cumulative total shareholder return to our peer group total shareholder return, and (iii) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our global net product revenues (the CSM), in each case for the years 2021 through 2025.

  PEO CAP   Non-PEO Avg CAP   Net Income (Loss)

Compensation Actually Paid vs. Company Selected Measure

The following graphs reflect the relationships between (i) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our net income (loss), (ii) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our cumulative total shareholder return and our cumulative total shareholder return to our peer group total shareholder return, and (iii) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our global net product revenues (the CSM), in each case for the years 2021 through 2025.

  PEO CAP   Non-PEO Avg CAP   Global Net Product Revenues

Total Shareholder Return Vs Peer Group

The following graphs reflect the relationships between (i) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our net income (loss), (ii) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our cumulative total shareholder return and our cumulative total shareholder return to our peer group total shareholder return, and (iii) CAP for our PEO, and the average of CAP for our non-PEO NEOs, to our global net product revenues (the CSM), in each case for the years 2021 through 2025.

  PEO CAP   Non-PEO Avg CAP   Alnylam TSR   Peer Group TSR

Tabular List, Table

Net product revenues

▪Collaboration and royalty revenues

▪Non-GAAP operating expenses*

▪Non-GAAP operating income (loss)*

Total Shareholder Return Amount

$ 305.96

181.05

147.27

182.85

130.48

Peer Group Total Shareholder Return Amount

124.75

93.49

94.03

89.90

100.02

Net Income (Loss)

$ 313,747,000

$ (278,157,000)

$ (440,242,000)

$ (1,131,156,000)

$ (852,824,000)

Company Selected Measure Amount

2,986,549,000

1,646,228,000

1,241,474,000

894,329,000

662,138,000

PEO Name

Yvonne L. Greenstreet, M.D.

Yvonne L. Greenstreet, M.D.

Yvonne L. Greenstreet, M.D.

Yvonne L. Greenstreet, M.D.

John M. Maraganore, Ph.D.

Additional 402(v) Disclosure

In calculating CAP reflected in these columns, the fair value or change in fair value, as applicable, of the equity award adjustments included in such calculations was determined in accordance with FASB ASC Topic 718. We did not report a change in pension benefit values for any of the years reflected in the table, and therefore adjustments to pension benefit values were not included in calculating CAP reflected in these columns, because we do not sponsor, maintain or contribute to a defined benefit pension plan.

Measure:: 1

Pay vs Performance Disclosure

Name

Net product revenues

Measure:: 2

Pay vs Performance Disclosure

Name

Collaboration and royalty revenues

Measure:: 3

Pay vs Performance Disclosure

Name

Non-GAAP operating expenses

Measure:: 4

Pay vs Performance Disclosure

Name

Non-GAAP operating income (loss)

PEO | Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

$ (9,875,880)

$ (7,239,400)

$ (6,744,150)

$ (2,498,790)

$ (7,861,410)

PEO | Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

34,291,241

17,187,024

8,173,520

5,823,820

9,100,080

PEO | Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

21,947,941

2,538,755

344,240

7,353,620

2,419,780

PEO | Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

16,197,619

5,857,154

741,014

3,776,000

3,679,210

Non-PEO NEO | Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

(5,105,633)

(1,688,240)

(1,888,468)

(2,548,800)

(4,891,560)

Non-PEO NEO | Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

10,365,563

3,978,386

2,288,708

5,582,350

6,583,990

Non-PEO NEO | Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

4,471,311

1,028,665

(852,294)

3,941,750

962,260

Non-PEO NEO | Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year

Pay vs Performance Disclosure

Adjustment to Compensation, Amount

$ 3,504,290

$ 1,488,254

$ (895,923)

$ 2,045,490

$ 2,140,690