Largest Company Tracker

The August books settled overnight and September opened with $68,154—and 42% of it bought one-in-667 outcomes. Polymarket's September board prices NVIDIA at 90.5% and Apple at 8.5%. Then it prices Amazon, Broadcom and SpaceX at 0.15% each—and those three legs took $18,424 between them, more than Apple, the only company with a plausible claim, took on its own.

Alphabet at 0.8% took $10,353, the third-busiest leg in the book. Between them, the four legs priced under one percent absorbed $28,776 of a $68,154 day.

The month and the year disagree by fifteen points. September gives NVIDIA 90.5%; December gives it 75.5%. The market is pricing roughly a one-in-seven chance that the crown changes hands in the fourth quarter alone, with Apple going from 8.5% to 15.05% across the same gap.

Manifold's untraded September board agrees to within a point and a half—NVIDIA 92.0%, Apple 6.0%—which is closer than a book with zero volume has any right to be.

And the persistence board says Broadcom is leaving. Broadcom still in the top seven at year end prices 13.1%, against 88% to 97.5% for the other six. Broadcom is simultaneously being priced out of the top seven and bought at 0.15% to be number one.

September's board against the December durable.

Polymarket's September book turns $68,154 against $150,537 held, and it is the busiest company-ranking contract on any supported exchange. NVIDIA 90.5%, Apple 8.5%, Alphabet 0.8%, then a floor of 0.15% legs.

December is the same field, fifteen points looser. NVIDIA 75.5%, Apple 15.05%, Alphabet 8.5%, SpaceX and Microsoft 1.05% each, on $16,134 and $435,205 of open interest. The three months between the two books carry all the doubt.

Beside them, Manifold's September mirror—NVIDIA 92.0%, Apple 6.0%—quoted and completely untraded.

The challenger is trading nearly as much as the leader, and the longshots are trading more than both.

NVIDIA's September leg at 90.5% took $12,396. Apple's at 8.5% took $10,728. On the December book the same pair took $5,590 and $5,201—Apple is within 7% of NVIDIA's volume on both horizons despite being priced at a tenth of it.

But the real flow is below one percent. Alphabet's September leg at 0.8% took $10,353; Amazon, Broadcom and SpaceX at 0.15% each took $6,715, $5,904 and $5,805. Four legs the book gives a combined 1.25% chance absorbed 42% of its day.

Below, the two December legs that matter: NVIDIA at 75.5% and Apple at 15.05%.

Rotation shape—second and third place for September.

Third place is a real question and it has a clear answer: Alphabet at 81.5%, with Microsoft at 11.5% and Apple at 7.5% behind it, on $4,071 and $22,208 held. NVIDIA appears here too, at 1.35%—a small but non-zero chance the largest company falls two places in four weeks.

Second place is Apple's at 85.0%, with NVIDIA at 6.0% and Alphabet at 5.0%, on Manifold's untraded board. Read together with first place, the three boards describe a settled hierarchy: NVIDIA, Apple, Alphabet, with only the top slot carrying real doubt and only in the fourth quarter.

Note the third-place board sums to about 101.9% and the first-place board to 100.25%—both close enough to be ordinary, unlike several of the sports boards elsewhere in this catalog.

Longer horizons and the IPO angle, all on Manifold, all essentially untraded.

The 2028 board is the interesting one. NVIDIA 19.3%, Apple 12.4%, Anthropic 10.9%, Microsoft 5.25%, Amazon 2.8%. On a two-year horizon the board gives a private AI lab a one-in-nine chance of being the most valuable company in the world—ahead of Microsoft and Amazon, and within nine points of NVIDIA. It has traded nothing, so treat it as a survey rather than a price, but it is the only place in this catalog where that question is asked at all.

The IPO board says the same thing. Largest 2026 IPO: Anthropic 54.7%, SpaceX 41.7%, OpenAI 3.5%.

And the persistence board says Broadcom leaves. Still in the top seven at year end: NVIDIA 97.5%, Apple 96.9%, Alphabet 95.4%, Microsoft 92.0%, Amazon 88.4%—and Broadcom 13.1%.

• 42% of September's opening day bought outcomes priced at or under 0.8%. Amazon, Broadcom and SpaceX at 0.15% took $18,424 between them and Alphabet at 0.8% took $10,353, against $12,396 for NVIDIA at 90.5%.
• Broadcom is being bought for first place and priced out of the top seven in the same session. $5,904 into a 0.15% leg to be the largest company, while the persistence board prices it at 13.1% to still be in the top seven at all.
• The month and the year are fifteen points apart on NVIDIA—90.5% for September, 75.5% for December. All of the doubt about the crown is in the fourth quarter.
• Manifold's untraded September board is within a point and a half of Polymarket's $68,154 one. NVIDIA 92.0% against 90.5%.
• Manifold gives Anthropic a one-in-nine shot at being the world's largest company by end-2028—10.9%, ahead of Microsoft and Amazon—and a 54.7% chance of being 2026's largest IPO. Zero volume, but the only place the question is priced.
• Third place is Alphabet's at 81.5% and second is Apple's at 85.0%, so only the top slot is genuinely contested.
• December's book holds $435,205 against $16,134 of flow. The durable book is where the position sits; the monthly is where the trading happens.