Who owns MEMX
Which tracked institutional funds hold MEMX, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MEMX company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-08-19). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
The tracked-fund tape on MEMX is one-sided between 2026-Q1 and 2026-Q2: 4 added or opened and 0 trimmed or exited — on balance accumulating.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
MEMX’s largest tracked holder by dollar value, MENLO ADVISORS LLC, sizes it at 2.2% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 2.2pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in MEMX divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 17 tracked filers holding MEMX, 7 increased or opened the position and 6 reduced or closed it; over the same quarter, there were no open-market insider Form 4s.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in MEMX between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
Largest adds
- Quattro Advisors LLC$1M
- Ameritas Advisory Services, LLC$517K
- LPL Financial LLC$435K
- Rockefeller Capital Management L.P.$354K
Institutional holders
One row per tracked fund, largest reported value first. “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding. Rows marked stale are from an earlier filing than the security’s latest quarter — that fund is absent from the newest snapshot (position exited, or reported under a different name).
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| Quattro Advisors LLC added | 56,369 | $3M | 19.4% | 2026-Q2 |
| LPL Financial LLC added | 32,689 | $2M | 11.3% | 2026-Q2 |
| Chicago Partners Investment Group LLC | 23,751 | $1M | 7.5% | 2026-Q2 |
| Rockefeller Capital Management L.P. added | 20,543 | $1M | 7.1% | 2026-Q2 |
| Ameritas Advisory Services, LLC added | 16,803 | $839K | 5.8% | 2026-Q2 |
| CITADEL ADVISORS LLC trimmed | 12,942 | $647K | 4.5% | 2026-Q2 |
| ENVESTNET ASSET MANAGEMENT INC added | 9,148 | $457K | 3.1% | 2026-Q2 |
| OLD MISSION CAPITAL LLC trimmed | 8,221 | $411K | 2.8% | 2026-Q2 |
| JANE STREET GROUP, LLC trimmed | 7,755 | $387K | 2.7% | 2026-Q2 |
| MERCER GLOBAL ADVISORS INC /ADV trimmed | 7,421 | $371K | 2.6% | 2026-Q2 |
| CASTLE WEALTH MANAGEMENT LLC | 5,713 | $285K | 2.0% | 2026-Q2 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP trimmed | 4,867 | $243K | 1.7% | 2026-Q2 |
| INTERNATIONAL ASSETS INVESTMENT MANAGEMENT, LLC trimmed | 2,855 | $138K | 0.9% | 2026-Q2 |
| Essential Investment Partners LLC | 2,000 | $100K | 0.7% | 2026-Q2 |
| UBS Group AG trimmed | 268 | $13K | 0.1% | 2026-Q2 |
| Spire Wealth Management | 65 | $3K | 0.0% | 2026-Q2 |
| OSAIC HOLDINGS, INC. trimmed | 56 | $3K | 0.0% | 2026-Q2 |
| MENLO ADVISORS LLC trimmed | 123,590 | $4M | 27.9% | 2025-Q2 stale (4 quarters behind) |
| CONCOURSE FINANCIAL GROUP SECURITIES, INC. | 0 | — | 0.0% | 2025-Q2 stale (4 quarters behind) |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.