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Livermore
Livermore
ZHEN

Primecap Management Co

SEC CIK
0000763212
Latest filing
Aug 14, 2026

The latest 13F from Primecap Management Co covers Q2 2026 (filed Aug 14, 2026): 324 long positions worth $169.1B. The top 10 holdings make up 42.6% of the portfolio, and the largest is Micron Technology Inc (MU) at 13.1%. Livermore has 22 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
11
Est. +$1.14B
Added
82
Est. +$3.47B
Reduced
179
Est. −$7.90B
Sold out
7
Est. −$209.5M

Top 5 holdings

Share of this quarter's portfolio value

  1. MUMicron Technology Inc
    13.1%$22.2BHistory
  2. LLYEli Lilly & Co
    6.5%$11.0BHistory
  3. INTCIntel Corp
    6.2%$10.5BHistory
  4. KLACKLA Corp
    3.7%$6.20BHistory
  5. GOOGLAlphabet Inc.
    3.1%$5.31BHistory

Biggest buys

New and added positions, by estimated amount bought

  1. BSXBoston Scientific Corp
    +$767.9MAddedHistory
  2. FDXFFedEx Freight Holding Company, Inc.
    +$611.3MNewHistory
  3. AALAmerican Airlines Group Inc.
    +$392.9MAddedHistory
  4. ILMNIllumina, Inc.
    +$254.5MAddedHistory
  5. SPCXSpace Exploration Technologies Corp
    +$240.5MNewHistory

Largest weight increases

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

  1. FDXFFedEx Freight Holding Company, Inc.
    +0.36 pp0.0% → 0.4%History
  2. AALAmerican Airlines Group Inc.
    +0.34 pp0.4% → 0.8%History
  3. UALUnited Airlines Holdings, Inc.
    +0.18 pp1.1% → 1.3%History
  4. XMTRXometry, Inc.
    +0.17 pp0.2% → 0.4%History
  5. ILMNIllumina, Inc.
    +0.16 pp0.2% → 0.4%History

Biggest sells

Reduced and sold-out positions, by estimated amount sold

  1. MUMicron Technology Inc
    −$3.07BReducedHistory
  2. KLACKLA Corp
    −$1.16BReducedConverted for a 10-for-1 splitHistory
  3. AMGNAmgen Inc
    −$766.7MReducedHistory
  4. TXNTexas Instruments Inc
    −$339.7MReducedHistory
  5. FLEXFlex Ltd.
    −$328.1MReducedHistory

Largest weight decreases

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

  1. AMGNAmgen Inc
    −1.01 pp2.5% → 1.4%History
  2. FDXFedEx Corp
    −0.82 pp2.3% → 1.5%History
  3. AZNAstraZeneca PLC
    −0.80 pp2.8% → 2.0%History
  4. BABAAlibaba Group Holding Ltd
    −0.79 pp1.8% → 1.1%History
  5. MSFTMicrosoft Corp
    −0.54 pp2.1% → 1.6%History

Metrics

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

Portfolio value
$169.1B
+$42.1B (+33.1%) vs. prior quarter
Positions
324
+4 vs. prior quarter
Top 10 concentration
42.6%
Top 10 as share of value
Turnover
3.1%
Q2 2026, one quarter
Average holding period
20.5 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

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

Peak $169.1B (Q2 2026)

Q1 2021: $143.4BQ2 2021: $148.8BQ3 2021: $141.7BQ4 2021: $144.5BQ1 2022: $132.6BQ2 2022: $111.9BQ3 2022: $103.3BQ4 2022: $109.2BQ1 2023: $114.7BQ2 2023: $119.7BQ3 2023: $118.5BQ4 2023: $126.3BQ1 2024: $134.1BQ2 2024: $138.1BQ3 2024: $136.0BQ4 2024: $129.1BQ1 2025: $121.0BQ2 2025: $126.2BQ3 2025: $130.6BQ4 2025: $132.1BQ1 2026: $127.0BQ2 2026: $169.1B
Q1 2021Q2 2026
13F filings of Primecap Management Co by quarter
QuarterFiledPositionsValueTop 3 holdingsChangesFiling
Q2 2026Aug 14, 2026324$169.1BMULLYINTCvs. Q1 2026SEC
Q1 2026May 11, 2026320$127.0BLLYMUGOOGLvs. Q4 2025SEC
Q4 2025Feb 11, 2026319$132.1BLLYMUGOOGLvs. Q3 2025SEC
Q3 2025Nov 12, 2025327$130.6BLLYMUMSFTvs. Q2 2025SEC
Q2 2025Aug 11, 2025333$126.2BLLYMSFTKLACvs. Q1 2025SEC
Q1 2025May 9, 2025335$121.0BLLYAMGNBSXvs. Q4 2024SEC
Q4 2024Feb 10, 2025329$129.1BLLYMSFTFDXvs. Q3 2024SEC
Q3 2024Nov 8, 2024336$136.0BLLYAMGNMSFTvs. Q2 2024SEC
Q2 2024Aug 9, 2024332$138.1BLLYMUKLACvs. Q1 2024SEC
Q1 2024May 14, 2024335$134.1BLLYMUMSFTvs. Q4 2023SEC
Q4 2023Feb 9, 2024334$126.3BLLYBIIBAMGNvs. Q3 2023SEC
Q3 2023Nov 13, 2023331$118.5BLLYBIIBAMGNvs. Q2 2023SEC
Q2 2023Aug 11, 2023328$119.7BLLYBIIBMSFTvs. Q1 2023SEC
Q1 2023May 15, 2023331$114.7BLLYBIIBAMGNvs. Q4 2022SEC
Q4 2022Feb 13, 2023334$109.2BLLYBIIBAMGNvs. Q3 2022SEC
Q3 2022Nov 14, 2022335$103.3BLLYBIIBAMGNvs. Q2 2022SEC
Q2 2022Aug 11, 2022341$111.9BLLYMSFTAMGNvs. Q1 2022SEC
Q1 2022May 11, 2022339$132.6BLLYMSFTAMGNvs. Q4 2021SEC
Q4 2021Feb 11, 2022342$144.5BLLYMSFTMUvs. Q3 2021SEC
Q3 2021Nov 12, 2021337$141.7BLLYMSFTBIIBvs. Q2 2021SEC
Q2 2021Aug 10, 2021333$148.8BLLYBIIBMSFTvs. Q1 2021SEC
Q1 2021May 14, 2021327$143.4BLLYBIIBMSFT–SEC

13D and 13G filings

Companies where Primecap Management Co reports owning 5% or more on Schedule 13D or 13G, and its latest filings.

Current stakes of 5% or more

20 companies, largest stake first.

Companies where Primecap Management Co owns 5% or more
CompanyLatest formStakeChangeFirst filedLatest filingFiling
XNCRXencor Inc13G/A14.79%10.5M shares–Feb 12, 20217 filingsAug 14, 2025SEC
XMTRXometry, Inc.13G/A12.90%6.50M shares+1.48 ppfrom 11.42%May 9, 20235 filingsMay 13, 2026SEC
LUNGPulmonx Corp13G/A12.16%4.96M shares−1.45 ppfrom 13.61%Dec 9, 20216 filingsNov 13, 2025SEC
AALAmerican Airlines Group Inc.13G/A10.46%69.2M shares+2.94 ppfrom 7.52%Feb 12, 20217 filingsJun 5, 2026SEC
MATMattel Inc13G/A10.29%33.2M shares–Feb 12, 20215 filingsAug 14, 2025SEC
BIIBBiogen Inc.13G/A10.20%15.0M shares–Feb 12, 20215 filingsNov 13, 2025SEC
MKTXMarketaxess Holdings Inc13G/A9.86%3.50M shares+1.32 ppfrom 8.54%Nov 13, 20253 filingsAug 6, 2026SEC
LUVSouthwest Airlines Co13G/A9.58%47.1M shares–Feb 12, 20215 filingsMay 13, 2026SEC
ELANElanco Animal Health Inc13G/A9.22%45.8M shares–Feb 12, 20216 filingsMay 13, 2026SEC
BMRNBiomarin Pharmaceutical Inc13G/A8.24%15.8M shares–Jan 7, 20216 filingsAug 14, 2025SEC
LIVNLivaNova PLC13G/A7.74%4.22M shares−1.02 ppfrom 8.76%Feb 12, 20217 filingsFeb 12, 2026SEC
IMCRImmunocore Holdings plc13G/A7.51%3.77M shares+2.18 ppfrom 5.33%Feb 13, 20252 filingsAug 14, 2025SEC
ACMAecom13G/A7.24%9.58M shares−1.35 ppfrom 8.59%Feb 12, 20216 filingsAug 14, 2025SEC
FLEXFlex Ltd.13G/A6.38%23.4M shares−1.51 ppfrom 7.89%Feb 12, 20217 filingsAug 6, 2026SEC
GKOSGLAUKOS Corp13G5.88%3.38M sharesNewFeb 11, 20261 filingFeb 11, 2026SEC
WHRWhirlpool Corp13G/A5.78%3.75M shares−1.02 ppfrom 6.80%Feb 12, 20216 filingsMay 13, 2026SEC
BAHBooz Allen Hamilton Holding Corp13G5.34%6.40M sharesNewAug 6, 20261 filingAug 6, 2026SEC
RYTMRhythm Pharmaceuticals, Inc.13G/A5.21%3.48M shares−1.21 ppfrom 6.42%Feb 12, 202111 filingsFeb 12, 2026SEC
GRALGRAIL, Inc.13G/A5.08%21.8M shares+0.36 ppfrom 4.72%Nov 12, 20244 filingsAug 6, 2026SEC
AMTMAmentum Holdings, Inc.13G5.03%12.3M sharesNewAug 6, 20261 filingAug 6, 2026SEC

Latest filings

222 filings on file made by Primecap Management Co or listing it as a reporting person; the latest 20 are shown.

Schedule 13D and 13G filings by Primecap Management Co
CompanyFiled (ET)FormStakeChangeEvent dateFiling
AMTMAmentum Holdings, Inc.Aug 6, 20265:16 PM ET13G5.03%12.3M sharesNewJun 30, 2026SEC
GRALGRAIL, Inc.Aug 6, 20265:01 PM ET13G/A5.08%21.8M shares+0.36 ppfrom 4.72%Jun 30, 2026SEC
BAHBooz Allen Hamilton Holding CorpAug 6, 20264:54 PM ET13G5.34%6.40M sharesNewJun 30, 2026SEC
FLEXFlex Ltd.Aug 6, 20264:28 PM ET13G/A6.38%23.4M shares−1.51 ppfrom 7.89%Jun 30, 2026SEC
MKTXMarketaxess Holdings IncAug 6, 20264:14 PM ET13G/A9.86%3.50M shares+1.32 ppfrom 8.54%Jun 30, 2026SEC
AALAmerican Airlines Group Inc.Jun 5, 20261:09 PM ET13G/A10.46%69.2M shares+2.94 ppfrom 7.52%May 31, 2026SEC
XMTRXometry, Inc.May 13, 20269:34 AM ET13G/A12.90%6.50M shares+1.48 ppfrom 11.42%Mar 31, 2026SEC
WHRWhirlpool CorpMay 13, 20269:34 AM ET13G/A5.78%3.75M shares−1.02 ppfrom 6.80%Mar 31, 2026SEC
LUVSouthwest Airlines CoMay 13, 20269:34 AM ET13G/A9.58%47.1M shares–Mar 31, 2026SEC
ELANElanco Animal Health IncMay 13, 20269:34 AM ET13G/A9.22%45.8M shares–Mar 31, 2026SEC
XMTRXometry, Inc.Feb 12, 202610:09 AM ET13G/A11.42%5.68M shares−1.56 ppfrom 12.98%Dec 31, 2025SEC
RYTMRhythm Pharmaceuticals, Inc.Feb 12, 202610:08 AM ET13G/A5.21%3.48M shares−1.21 ppfrom 6.42%Dec 31, 2025SEC
LIVNLivaNova PLCFeb 12, 202610:08 AM ET13G/A7.74%4.22M shares−1.02 ppfrom 8.76%Dec 31, 2025SEC
WHRWhirlpool CorpFeb 11, 202612:57 PM ET13G/A6.80%3.82M shares–Dec 31, 2025SEC
UALUnited Airlines Holdings, Inc.Feb 11, 202612:56 PM ET13G/A4.88%16.0M shares−0.87 ppfrom 5.75%Below 5%Dec 31, 2025SEC
NXTNextpower Inc.Feb 11, 202612:56 PM ET13G/A4.68%6.95M shares–Below 5%Dec 31, 2025SEC
MKTXMarketaxess Holdings IncFeb 11, 202612:56 PM ET13G/A8.54%3.18M shares+2.57 ppfrom 5.97%Dec 31, 2025SEC
GRALGRAIL, Inc.Feb 11, 202612:55 PM ET13G/A4.72%1.84M shares−1.00 ppfrom 5.72%Below 5%Dec 31, 2025SEC
GKOSGLAUKOS CorpFeb 11, 202612:55 PM ET13G5.88%3.38M sharesNewDec 31, 2025SEC
NTAPNetApp, Inc.Nov 14, 202512:16 PM ET13G/A4.82%9.63M shares−1.19 ppfrom 6.01%Below 5%Sep 30, 2025SEC