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Livermore
Livermore
ZHEN

Mass General Brigham, Inc

SEC CIK
0001678378
Latest filing
Aug 7, 2026

The latest 13F from Mass General Brigham, Inc covers Q2 2026 (filed Aug 7, 2026): 6 long positions worth $361.1M. The top 10 holdings make up 100.0% of the portfolio, and the largest is iShares Tr at 54.8%. Livermore has 18 filings on Form 13F from this institution, going back to Q1 2021.

What changed in Q2 2026

Share counts compared with Q1 2026: how many positions were new, added to, reduced or sold out, and the biggest buys and sells. Dollar amounts are estimated at the quarter-end prices implied by the filing.

Full comparison
New
0
Added
0
Reduced
2
Est. −$140.4M
Sold out
0

Top 5 holdings

Share of this quarter's portfolio value

  1. iShares Tr464288257
    54.8%$197.7M
  2. KRMNKarman Holdings Inc.
    21.6%$78.0MHistory
  3. RVMDRevolution Medicines, Inc.
    17.8%$64.4MHistory
  4. TNGXTango Therapeutics, Inc.
    3.1%$11.1MHistory
  5. MAZEMaze Therapeutics, Inc.
    2.0%$7.16MHistory

Share of portfolio

Top 5 holdings and the other 1 position, by share of portfolio value

  1. iShares Tr54.8%
  2. KRMN21.6%
  3. RVMD17.8%
  4. TNGX3.1%
  5. MAZE2.0%
  6. Other 1 position0.7%

Biggest buys

New and added positions, by estimated amount bought

None this quarter.

Largest weight increases

New and added positions, by percentage points of the portfolio gained

None this quarter.

Biggest sells

Reduced and sold-out positions, by estimated amount sold

  1. iShares Tr464288257
    −$140.3MReduced
  2. MDLNMedline Inc.
    −$76.7KReducedHistory

Largest weight decreases

Reduced and sold-out positions, by percentage points of the portfolio lost

  1. iShares Tr464288257
    −7.66 pp62.4% → 54.8%

Metrics

13F metrics for Q2 2026, computed only from the numbers in the filings. Definitions below.

Portfolio value
$361.1M
−$107.8M (−23.0%) vs. prior quarter
Positions
6
0 vs. prior quarter
Top 10 concentration
100.0%
Top 10 as share of value
Turnover
0.0%
Q2 2026, one quarter
Average holding period
3.0 quarters
Weighted by value

How these are calculated

  • Portfolio value: the market value of all long positions in the 13F, as reported at quarter end, excluding options.
  • Top 10 concentration: the combined value of the 10 largest positions as a share of portfolio value.
  • Turnover: the smaller of this quarter's estimated purchases and estimated sales, divided by the average of this and last quarter's portfolio value. Estimates multiply the change in shares by the quarter-end price implied by the filing (market value divided by shares); new positions use this quarter's value and sold-out positions last quarter's. Only positions reported in shares count, and it is not calculated when the previous quarter was not filed.
  • Average holding period: how many consecutive quarters each current position has been held (including this one; a quarter without the position or without a filing starts the count over), weighted by this quarter's value. Counting starts with the first 13F in Livermore (Q1 2021), so positions held before then are understated.

13F filings by quarter

18 quarters, going back to Q1 2021. Bars show each quarter's 13F portfolio value; quarters without a filing are left blank.

Peak $809.8M (Q4 2025)

Q1 2021: $639.4MQ2 2021: $409.9MQ3 2021: $370.6MQ4 2021: $282.0MQ1 2022: $235.1MQ2 2022: $213.8MQ3 2022: $192.3MQ4 2022: $140.5MQ1 2023: $128.3MQ2 2023: $109.9MQ3 2023: $10.8MQ4 2023: $28.0MQ1 2024: $57.1MQ2 2024: $20.5MQ3 2024: $43.6MQ4 2025: $809.8MQ1 2026: $468.9MQ2 2026: $361.1M
Q1 2021Q2 2026
13F filings of Mass General Brigham, Inc by quarter
QuarterFiledPositionsValueTop 3 holdingsChangesFiling
Q2 2026Aug 7, 20266$361.1MiShares TrKRMNRVMDvs. Q1 2026SEC
Q1 2026May 5, 20266$468.9MiShares TrKRMNRVMDvs. Q4 2025SEC
Q4 2025Jan 27, 20267$809.8MiShares TrKRMNRVMD–SEC
Q3 2024Oct 16, 20245$43.6MIOTRVMDPLRXvs. Q2 2024SEC
Q2 2024Jul 31, 20244$20.5MRVMDPLRXTNGXvs. Q1 2024SEC
Q1 2024Apr 4, 20245$57.1MCOINRVMDPLRXvs. Q4 2023SEC
Q4 2023Jan 24, 20242$28.0MCOINSNOWvs. Q3 2023SEC
Q3 2023Oct 23, 20232$10.8MCOINRIVNvs. Q2 2023SEC
Q2 2023Jul 21, 20237$109.9MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFIOTvs. Q1 2023SEC
Q1 2023Apr 5, 20236$128.3MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFCOINvs. Q4 2022SEC
Q4 2022Jan 19, 20235$140.5MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFCOINvs. Q3 2022SEC
Q3 2022Oct 19, 20223$192.3MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFCOINvs. Q2 2022SEC
Q2 2022Jul 27, 20223$213.8MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFCOINvs. Q1 2022SEC
Q1 2022Apr 15, 20225$235.1MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFCOINvs. Q4 2021SEC
Q4 2021Jan 19, 20227$282.0MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFCOINvs. Q3 2021SEC
Q3 2021Oct 8, 20217$370.6MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFCOINvs. Q2 2021SEC
Q2 2021Jul 19, 20219$409.9MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFCOINvs. Q1 2021SEC
Q1 2021Apr 12, 20213$639.4MiShares Core S&P 500 ETFiShares Core U.S. Aggregate Bond ETFiShares Tr–SEC