RIA Aggregator 13Fs vs Active Manager 13Fs: A Reader's Guide

Two institutional managers both file 13F-HR forms. Both report $90B+ in market value. Both appear in the same top-100 filer lists. From the outside, they look the same. From inside the data, they are completely different categories of filing — and confusing the two is the single most common mistake retail investors make when reading institutional ownership signals.

One is an RIA aggregator — a wealth-management platform that aggregates equity holdings across thousands of advisor-managed client accounts. The other is an active manager — a discretionary investment firm whose portfolio reflects a small team's investment view. This guide walks through how to tell them apart, and what each filing actually means.

The structural difference: position count

The clearest tell is the number of distinct positions in the 13F.

• Active managers typically report 30-200 positions. A high-conviction equity hedge fund might run 30. A diversified mutual fund family like Capital International might run 100-150. A multi-strategy platform like Citadel Advisors LLC reports thousands of positions, but on closer look those break into ~50-100 high-conviction equity lines plus many small derivative/inventory positions.
• RIA aggregators typically report 2,000-5,000+ positions. HighTower Advisors LLC, for example, reported 3,796 positions in its 2026Q1 13F. Mariner Wealth, Creative Planning, and Focus Financial show similar shapes.

The mechanical reason: an RIA aggregator's 13F is the pooled aggregation of every individual position held in every client account across every advisor on the platform. Each advisor's model portfolio is different, each client has different tax constraints or preference overrides, and the regulatory requirement is to disclose the aggregate. The output is a 13F with thousands of sub-1% lines.

The conviction signal: top-10 concentration

Position count alone isn't proof — some quant funds run thousands of small statistical-arbitrage positions and aren't aggregators. The second indicator is concentration.

• Active managers usually have a top-10 weight of 30-60% of their book. A high-conviction concentrated manager like PRIMECAP or Pzena will run higher; a diversified active fund will sit closer to 25-30%. Discretionary money goes into a small number of names.
• RIA aggregators typically have a top-10 weight of 15-25%. HighTower's top-10 was 22.0% in 2026Q1 — below the S&P 500's own top-10 concentration. The portfolio is structurally more diversified than the index it tracks.

For comparison, here's what the spread looks like in current filer data:

• Pzena Investment Management — concentrated active value, ~50% top-10 weight typical.
• PRIMECAP Management — concentrated growth, ~40% top-10 weight typical.
• Capital International Investors — diversified active, ~25-30% top-10 typical.
• HighTower (aggregator profile) — ~22% top-10.

Even the most diversified true active manager (Capital International at ~25-30%) runs higher concentration than the most representative aggregator (HighTower at 22%). The 5-percentage-point gap is enough to classify.

The ETF tell

The single most reliable indicator of an RIA aggregator: large positions in the same S&P 500 ETFs that retail investors hold.

Specifically, watch for:

• IVV (iShares Core S&P 500)
• SPY (SPDR S&P 500)
• VOO (Vanguard S&P 500)

An active manager almost never holds these ETFs in size — they buy individual stocks directly. If they want passive S&P 500 exposure, they use index futures (which don't show up on 13F) or they don't take that exposure at all. An RIA aggregator, by contrast, holds these ETFs because they are the default vehicle for client accounts that haven't been customized.

HighTower's 2026Q1 top 10 included IVV ($2.08B), SPY ($1.82B), and VOO ($1.58B) — three S&P 500 ETFs in the top 10 of the same filing. A discretionary active manager would never display that shape.

What each filing is actually useful for

Different filings serve different reader questions. Match the filing type to the question.

If you're trying to read institutional conviction on a specific stock

Read the active manager 13F. Their top-10 changes are deliberate decisions. A new position in a small-cap healthcare name from an active manager with $100B AUM is a strong signal — they researched it and bought enough to register. The same position size from an RIA aggregator is a rounding error.

If you're trying to read mass-affluent retail behavior

Read the RIA aggregator 13F. The aggregate weights — ETF percentage, mega-cap concentration, average position size — track what advisors are actually putting into client accounts. Changes quarter-over-quarter in the aggregator file approximate changes in the median wealth-management portfolio. That's a useful denominator.

If you're trying to read sector rotation

Read several active manager 13Fs at the same time. If three different concentrated active managers all increased their healthcare weighting in the same quarter, that's a sector signal. If an aggregator's healthcare weighting moved, it's likely just because the largest healthcare names appreciated.

If you're trying to read platform consolidation

Read the RIA aggregator's AUM history. Aggregator AUM growth that outpaces market returns reflects net advisor onboarding — the consolidation trend that has reshaped the US wealth-management industry over the past decade.

Common misreads

Misread #1: "Big fund bought $1B of AAPL — bullish!" If the big fund is an RIA aggregator, the position reflects thousands of small advisor-managed buys of Apple over time, not a single conviction decision. It's not bullish; it's mechanical.

Misread #2: "Active fund only owns 30 stocks — undiversified and risky!" A concentrated active fund holding 30 names is the typical shape for discretionary investing. The aggregate position count is not a risk indicator on its own — what matters is what's in those 30 names and how the manager sizes them.

Misread #3: "Fund's biggest position is the S&P 500 ETF — they don't have any view." If the fund's biggest position is IVV or SPY, the fund is almost certainly an aggregator. They have a view, but the view is distributed across thousands of advisor decisions; the ETF is the platform default. Don't conclude that the firm has "no opinion."

Quick classification checklist

When you encounter a new 13F filer name, ask:

• Does the firm's name contain "Advisors," "Wealth," "Partners" (in the RIA-aggregator sense), "Financial," or "Wealth Management"? — Often an aggregator.
• Does the position count exceed 1,500? — Almost certainly an aggregator or a quant fund (not an active discretionary manager).
• Are S&P 500 ETFs (IVV, SPY, VOO) in the top 10? — Almost certainly an aggregator.
• Is the top-10 concentration below 25%? — Likely an aggregator.
• Does the AUM exceed $50B AND the firm is unfamiliar in the active-management trade press? — Likely an aggregator.

If three or more of these hit, classify as aggregator and read the 13F accordingly. If two or fewer hit, treat as an active manager and read the position changes as deliberate signals.

For more on how 13F filings work and what they don't tell you, browse our explainer library or jump straight to the filer directory to see live examples of both filer types side by side. The SEC primary record for any 13F filer is at EDGAR's 13F-HR list.