Adage Capital's $66B Q4: 905 Holdings, Mega-Cap Anchored

Adage Capital Partners filed its Q4 2025 13F at $66.08B in reported assets across 905 positions. The position count is the headline. For context, the typical mega-cap-focused active manager files 60-150 names; a typical multi-strategy quant prints 500-1,500. Adage at 905 sits on the upper end of the diffuse-active spectrum — a portfolio shape inherited directly from the Boston endowment school where the founders trained.

What that 905-name breadth produces is a portfolio whose top weights mirror the U.S. mega-cap index almost line-for-line, while the tail does the active work. The top 10 holdings sum to roughly 33.2% of reported value. The remaining 895 names carry the other ~67%. This is not a high-conviction book in the conventional sense; it is an alpha-from-the-tail book.

Top 10: An Index in Active Clothing

The top 10 weights, ranked:

#	Ticker	Value	Weight
1	NVDA	$4.15B	6.63%
2	AAPL	$3.60B	5.74%
3	MSFT	$3.21B	5.12%
4	AMZN	$2.09B	3.34%
5	GOOGL	$1.64B	2.62%
6	AVGO	$1.46B	2.33%
7	META	$1.33B	2.12%
8	GOOG	$1.31B	2.09%
9	TSLA	$1.11B	1.77%
10	LLY	$894M	1.43%

That ranking is — within rounding — the S&P 500 mega-cap order. The GOOGL + GOOG combined Google position is 4.71%, putting Alphabet roughly third behind NVDA and AAPL. NVDA at 6.63% is meaningfully overweight relative to its S&P weight; AAPL at 5.74% is roughly neutral; the rest cluster within a percentage point of the index. The only line that deviates from index weight is the last one — Eli Lilly at 1.43%, which is the single significant non-tech name and the cleanest read on where Adage is leaning sector-wise outside the AI complex.

Concentration: Top vs. Tail

The bare concentration metrics — Top-1 = 6.63%, Top-5 = 23.45%, Top-10 = 33.19% — look modest for an active manager. That is by design. With 905 positions, the median holding is sub-$10M and most positions sit between 0.01% and 0.5% of AUM. The active alpha — to the extent it exists — comes from how the manager populates that long tail, not from how aggressively it sizes the top.

The implication for any reader using Adage as a signal source: do not read the top 10 as conviction. The top 10 is index exposure. The interesting expressions are in positions ranked 100-500, where the manager is making real over- and under-weight decisions relative to benchmarks. A position at, say, 0.3% of Adage's book is a $200M check — meaningful capital but invisible if you only scan the top.

AUM Trajectory: Steady, Not Spiky

Adage's AUM has compounded steadily over the past eight quarters, with no spike that suggests asset gathering or sudden inflow events:

• 2024Q1: $52.98B (864 holdings)
• 2024Q2: $54.01B (860)
• 2024Q3: $56.64B (864)
• 2024Q4: $57.19B (869)
• 2025Q1: $53.99B (837)
• 2025Q2: $59.35B (843)
• 2025Q3: $63.14B (872)
• 2025Q4: $66.08B (905)

That sequence — eight consecutive quarters in the $53-66B range, position counts holding in a tight 837-905 band — is the AUM signature of a stable institutional client base, not a hot-money product. The implied growth rate is roughly 24.7% over two years, much of which can be attributed to the mark-to-market on mega-cap tech rather than new-money inflows.

Filer Profile and Reading Notes

Adage Capital Partners was founded in 2001 by Robert Atchinson and Phillip Gross, both formerly of Harvard Management Company. The fund's structural DNA is endowment-style: long-only, diversified across hundreds of names, fundamental research at the security level, low turnover relative to a hedge fund. WhaleScore comes in at 66.50, in the middle of the active manager range. That mid-range score reflects the same trade-off the portfolio itself reflects: alpha generated through breadth and selection rather than concentration.

For investors who use 13F filings as conviction signals, Adage is a particular kind of filer. Top-line copying is structurally ineffective because the top is the index. The useful signals are: (1) new initiations between rank 50 and rank 200 — where the manager is committing meaningful capital to a non-mega-cap idea, (2) sized exits below rank 300 — where a position dropped to zero from a previously held 0.2-0.5% weight, and (3) sector tilts visible only in aggregate (e.g., the LLY weighting as a proxy for healthcare overweight).

What to Watch Next

1. Whether NVDA's 6.63% weight grows or compresses. A move toward 8%+ would be the clearest active conviction signal in the top of the book — Adage rarely takes a single name above 7%.
2. The LLY line. If LLY stays in the top 10 in Q1 2026 and grows, the healthcare-vs-tech rotation has a real signal here. If it drops below the top 20, the tech-dominance of the top is intact.
3. Position count stability. Watch whether the 905-name level holds. A drop below 800 would suggest portfolio concentration is being pushed deliberately; a rise above 950 would suggest further diversification.

The Read

Adage Capital is the cleanest example in our active-manager universe of a book built for breadth rather than conviction. The top 10 mirrors the index. The active work happens in the next 895 lines. For anyone using 13F data, this is the manager whose top-position copying produces the worst signal-to-noise ratio. The interesting signal is below rank 50.

Track the complete Adage Capital holdings, quarterly position changes, and full filing history at /filers/adage-capital-partners-gp-llc-0001165408. Compare across active managers at /filers; cross-reference signal flow at /insights.