Guy Spier - Aquamarine
Guy Spier runs the Aquamarine Fund with a Buffett-and-Munger-inspired value philosophy and wrote "The Education of a Value Investor." He famously won (with Mohnish Pabrai) a charity lunch with Warren Buffett.
Guy Spier - Aquamarine manages a $135M U.S. equity portfolio of 7 positions, based on the latest SEC Form 13F-HR filing (Q1 2026). Below you'll find every holding, the biggest quarter-over-quarter buys and sells, position weights, and an estimated average buy price.
Portfolio Value
$135M
Positions
7
Top 10 Weight
100.00%
Largest Position
34.57%
As of
Q1 2026
Filed
Apr 17, 2026
Portfolio Composition
Strategy Snapshot
- › Portfolio value fell 8.3% quarter-over-quarter to $135M.
- › Highly concentrated portfolio — the top 10 holdings make up 100.0% of assets.
- › This quarter: 0 new buys, 0 adds, 0 trims, 0 full exits — net buyer
Current Holdings
| # | Security | Value | % of Portfolio | Avg Buy Price | Price | Gain | vs 52W High | This Qtr | Last Activity | First Buy |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | BERKSHIRE HATHAWAY INC DEL BRK-B | $46M | 34.57% | ~$406.80 | $491.28 | +20.8% | −4.9% | UNCH | Sold Q4 2025 | Q2 2024 |
| 2 | BERKSHIRE HATHAWAY INC DEL BRK-A | $21M | 15.92% | ~$612233.33 | $737300.00 | +20.4% | −4.9% | UNCH | Bought Q2 2024 | Q2 2024 |
| 3 | MASTERCARD INC MA | $19M | 14.77% | ~$441.16 | $492.99 | +11.7% | −18.1% | UNCH | Sold Q4 2025 | Q2 2024 |
| 4 | AMERICAN EXPRESS CO AXP | $19M | 14.53% | ~$231.55 | $340.54 | +47.1% | −12.1% | UNCH | Sold Q4 2025 | Q2 2024 |
| 5 | MOODYS CORP MCO | $11M | 8.71% | ~$420.93 | $456.22 | +8.4% | −16.6% | UNCH | Bought Q2 2024 | Q2 2024 |
| 6 | FERRARI N V RACE | $10M | 7.40% | ~$407.85 | $354.28 | −13.1% | −31.8% | UNCH | Sold Q4 2025 | Q2 2024 |
| 7 | DAILY JOURNAL CORP DJCO | $5M | 4.10% | ~$394.52 | $535.06 | +35.6% | −20.7% | UNCH | Bought Q2 2024 | Q2 2024 |
Filing History
| Period | Portfolio Value | QoQ Change | Positions | Filed |
|---|---|---|---|---|
| Q1 2026 | $135M | −8.3% | 7 | Apr 17, 2026 |
| Q4 2025 | $147M | −53.5% | 7 | Jan 15, 2026 |
| Q3 2025 | $317M | +2.4% | 14 | Oct 20, 2025 |
| Q2 2025 | $309M | +5.5% | 14 | Jul 16, 2025 |
| Q1 2025 | $293M | +2.1% | 14 | Apr 11, 2025 |
| Q4 2024 | $287M | +0.7% | 14 | Jan 24, 2025 |
| Q3 2024 | $285M | +8.8% | 14 | Oct 16, 2024 |
| Q2 2024 | $262M | — | 14 | Jul 11, 2024 |
Frequently Asked Questions
What stocks does Guy Spier - Aquamarine own?
As of Q1 2026, Guy Spier - Aquamarine held 7 U.S.-listed positions worth $135M. The largest is BERKSHIRE HATHAWAY INC DEL (BRK-B) (34.57% of the portfolio). The full holdings list is in the table above.
What is Guy Spier - Aquamarine's largest holding?
BERKSHIRE HATHAWAY INC DEL (BRK-B) — about 34.57% of the equity portfolio as of Q1 2026.
Do these holdings reflect Guy Spier - Aquamarine's current portfolio?
They reflect the latest 13F filing (Q1 2026), which can lag actual trades by up to 45 days and excludes short positions, cash, and non-U.S. holdings.