Main Street Advisors is an SEC-registered investment adviser based in Santa Monica, CA that reports managing 1 hedge fund on Form ADV. It reports $9.6 billion in regulatory assets under management. Its private funds, of all types, hold $1.8 billion in gross assets. Its disclosed U.S. stock holdings returned an estimated -1.9% 2026 YTD through Jun 30 (S&P 500: +9.5%), based on 13F filings. Over a longer period they returned an estimated +22.8% from Q3 2024 to Q2 2026, compared with +37.2% for the S&P 500, based on 13F filings.
- Regulatory assets under management
- $9.6 billionForm ADV Item 5.F
- Gross assets of private funds
- $1.8 billionAll private fund types, Form ADV
- Hedge funds managed
- 16 private funds in total
- Employees
- 34Form ADV Item 5.A
- Registration
- SEC-registered adviserCRD 305170
- Latest Form ADV
- 03/27/2026Disciplinary disclosures: none reported
Estimated 13F portfolio performance
Estimated by AltMountain, derived from the firm’s public Form 13F filings. Not reported by the firm and not the return of any fund.
| Quarter | Est. 13F return | S&P 500 |
|---|---|---|
| Q2 2026 | +10.8% | +14.8% |
| Q1 2026 | -11.5% | -4.6% |
| Q4 2025 | +3.1% | +2.4% |
| Q3 2025 | +2.3% | +7.8% |
| Q2 2025 | +8.7% | +10.4% |
| Q1 2025 | -9.3% | -4.5% |
| Q4 2024 | +12.6% | +2.1% |
| Q3 2024 | +6.9% | +5.4% |
Estimate of the firm's disclosed long U.S. stock portfolio from its quarterly 13F filings, holding each quarter-end portfolio to the next quarter-end at prices implied by all 13F filers. It is a price return before dividends and fees, ignores shorts, options, bonds, cash and trading within the quarter, and is not the return of any fund. Disclosures
Manager of this firm? Report your fund’s actual net return, or email hello@altmountain.com to correct or remove this estimate. Removal requests from the firm are honored.
13F holdings as of Jun 30, 2026
All 43 share positions ($388,570,841) reported by MSA Advisors, LLC on Form 13F for the quarter ended Jun 30, 2026, filed Aug 14, 2026. Shown as filed with the SEC. Original filing on SEC.gov ↗
| Stock | Value | % of 13F portfolio | Shares | Shares vs prior quarter |
|---|---|---|---|---|
| Apollo Global Mgmt Inc | $92,406,262 | 23.78% | 781,052 | -9.58% |
| State STR SPDR S&P 500 ETF T | $52,869,822 | 13.61% | 70,798 | -7.73% |
| Starbucks Corp | $34,801,520 | 8.96% | 340,557 | -1.02% |
| Live Nation Entertainment In | $31,054,724 | 7.99% | 169,596 | -9.11% |
| Alphabet Inc | $27,771,738 | 7.15% | 78,600 | -9.10% |
| Apple Inc | $27,255,397 | 7.01% | 94,192 | +2.42% |
| Ishares TR | $18,559,613 | 4.78% | 28,965 | New |
| Microsoft Corp | $15,168,858 | 3.90% | 40,665 | +5.30% |
| Meta Platforms Inc | $13,013,689 | 3.35% | 23,103 | -4.94% |
| Spotify Technology S A | $12,284,023 | 3.16% | 26,755 | +434.57% |
| Jpmorgan Chase & Co | $9,950,832 | 2.56% | 30,400 | Unchanged |
| Nvidia Corporation | $7,570,005 | 1.95% | 37,833 | +359.53% |
| Eli Lilly & Co | $7,494,039 | 1.93% | 6,248 | Unchanged |
| TPG Inc | $6,872,941 | 1.77% | 169,493 | Unchanged |
| Gap Inc | $5,768,384 | 1.48% | 308,800 | New |
| Strategy Inc | $2,806,970 | 0.72% | 32,290 | Unchanged |
| Dimensional ETF Trust | $2,241,944 | 0.58% | 53,725 | Unchanged |
| Shopify Inc | $2,226,510 | 0.57% | 19,500 | Unchanged |
| Liberty Media Corp Del | $2,135,101 | 0.55% | 24,390 | New |
| Klarna Group PLC | $2,019,304 | 0.52% | 99,768 | Unchanged |
| Disney Walt Co | $1,667,430 | 0.43% | 17,190 | Unchanged |
| Dimensional ETF Trust | $1,515,921 | 0.39% | 21,687 | Unchanged |
| Vanguard Index FDS | $1,437,493 | 0.37% | 2,093 | Unchanged |
| Bank Of Amer Corp | $1,278,232 | 0.33% | 22,433 | Unchanged |
| Dimensional ETF Trust | $961,720 | 0.25% | 24,793 | Unchanged |
| The Beachbody Company Inc | $920,669 | 0.24% | 90,085 | Unchanged |
| Uber Technologies Inc | $828,180 | 0.21% | 11,477 | -23.11% |
| Schwab Strategic TR | $651,607 | 0.17% | 20,952 | Unchanged |
| Dell Technologies Inc | $636,404 | 0.16% | 1,475 | Unchanged |
| Tesla Inc | $609,449 | 0.16% | 1,449 | -32.26% |
| Comcast Corp New | $564,355 | 0.15% | 22,988 | Unchanged |
| Amazon Com Inc | $560,099 | 0.14% | 2,350 | Unchanged |
| Palantir Technologies Inc | $533,415 | 0.14% | 4,572 | -28.81% |
| Berkshire Hathaway Inc Del | $383,299 | 0.10% | 766 | Unchanged |
| Caris Life Sciences Inc | $342,144 | 0.09% | 19,200 | Unchanged |
| Nike Inc | $293,122 | 0.08% | 7,070 | Unchanged |
| Coca Cola Cons Inc | $232,922 | 0.06% | 1,220 | Unchanged |
| Cloudflare Inc | $219,526 | 0.06% | 895 | Unchanged |
| Rocket Cos Inc | $183,393 | 0.05% | 11,644 | Unchanged |
| Sentinelone Inc | $181,223 | 0.05% | 10,679 | Unchanged |
| Satellogic Inc | $150,213 | 0.04% | 26,261 | Unchanged |
| Peloton Interactive Inc | $107,657 | 0.03% | 18,216 | Unchanged |
| Denison Mines Corp | $40,692 | 0.01% | 13,298 | New |
Changes since Mar 31, 2026
Comparing the share counts in the two quarter-end filings: 4 new positions, 11 sold out, 4 increased, 9 reduced and 26 unchanged.
New positions
| Stock | Value | Shares |
|---|---|---|
| Ishares TR | $18,559,613 | 28,965 |
| Gap Inc | $5,768,384 | 308,800 |
| Liberty Media Corp Del | $2,135,101 | 24,390 |
| Denison Mines Corp | $40,692 | 13,298 |
Sold out
| Stock | Value at Mar 31, 2026 | Shares held then |
|---|---|---|
| Oklo Inc | $226,924 | 4,576 |
| BWX Technologies Inc | $193,652 | 947 |
| Tko Group Holdings Inc | $165,555 | 821 |
| 2023 ETF Series Trust | $153,621 | 5,050 |
| Pinterest Inc | $149,838 | 8,170 |
| Birkenstock Holding PLC | $146,903 | 4,100 |
| Ishares TR | $143,500 | 656 |
| Take-two Interactive Softwar | $139,435 | 706 |
| Novo-nordisk A S | $128,625 | 3,500 |
| Ishares TR | $120,279 | 963 |
| Grab Holdings Limited | $61,781 | 16,880 |
Largest increases
| Stock | Change in shares | Change | Value now | Shares now |
|---|---|---|---|---|
| Spotify Technology S A | +21,750 | +434.57% | $12,284,023 | 26,755 |
| Nvidia Corporation | +29,600 | +359.53% | $7,570,005 | 37,833 |
| Microsoft Corp | +2,045 | +5.30% | $15,168,858 | 40,665 |
| Apple Inc | +2,225 | +2.42% | $27,255,397 | 94,192 |
Largest reductions
| Stock | Change in shares | Change | Value now | Shares now |
|---|---|---|---|---|
| Apollo Global Mgmt Inc | -82,750 | -9.58% | $92,406,262 | 781,052 |
| State STR SPDR S&P 500 ETF T | -5,930 | -7.73% | $52,869,822 | 70,798 |
| Live Nation Entertainment In | -17,000 | -9.11% | $31,054,724 | 169,596 |
| Alphabet Inc | -7,865 | -9.10% | $27,771,738 | 78,600 |
| Meta Platforms Inc | -1,200 | -4.94% | $13,013,689 | 23,103 |
| Starbucks Corp | -3,500 | -1.02% | $34,801,520 | 340,557 |
| Tesla Inc | -690 | -32.26% | $609,449 | 1,449 |
| Uber Technologies Inc | -3,450 | -23.11% | $828,180 | 11,477 |
| Palantir Technologies Inc | -1,850 | -28.81% | $533,415 | 4,572 |
Each list shows up to 20 positions, largest first by dollar amount. Changes compare two quarter-end snapshots, with the earlier share count adjusted for stock splits AltMountain detected. They do not show when, or at what price, anything was bought or sold.
From public Form 13F filings, not verified. Form 13F is filed up to 45 days after the quarter ends, so positions may have changed. It lists only certain long positions in U.S.-listed stocks and exchange-traded funds; options are not shown here, and short positions, most bonds, cash, non-U.S. securities and private investments are not reported at all, so a holding may be one side of a hedge. A filing covers the manager as a whole, not any single fund, and filings contain errors. This is not investment advice or a recommendation to buy or sell any security. Disclosures
Private funds reported on Form ADV (6)
As reported in the adviser's Form ADV filed Jun 28, 2024. Funds also listed from Form D are shown above.
From SEC filings. Firm data comes from the SEC's Form ADV data as of Oct 2, 2026; performance estimates come from Form 13F. AltMountain has not verified this information, and it is not an offer, solicitation or recommendation. Full disclosures