Who owns MBSX
Which tracked institutional funds hold MBSX, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MBSX company fundamentals →
Ownership as of the 2026-Q1 13F filings. 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 MBSX is one-sided between 2025-Q4 and 2026-Q1: 2 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
MBSX’s largest tracked holder by dollar value, Castleview Partners, LLC, sizes it at 4.3% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 4.3pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in MBSX 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 2025-Q4 and 2026-Q1, across 8 tracked filers holding MBSX, 5 increased or opened the position and 4 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 MBSX between the 2025-Q4 and 2026-Q1 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
- Castleview Partners, LLC$739K
- Auour Investments LLC$378K
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 |
|---|---|---|---|---|
| Castleview Partners, LLC added | 299,717 | $8M | 53.0% | 2026-Q1 |
| Auour Investments LLC added | 120,891 | $3M | 21.4% | 2026-Q1 |
| Camarda Financial Advisors, LLC added | 66,876 | $2M | 11.8% | 2026-Q1 |
| BlackDiamond Wealth Management, LLC added | 31,659 | $892K | 5.6% | 2026-Q1 |
| CITADEL ADVISORS LLC trimmed | 15,376 | $433K | 2.7% | 2026-Q1 |
| JANE STREET GROUP, LLC trimmed | 11,599 | $327K | 2.0% | 2026-Q1 |
| Diesslin Group, Inc. new | 9,078 | $256K | 1.6% | 2026-Q1 |
| JPMORGAN CHASE & CO | 200 | $5K | 0.0% | 2026-Q1 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP trimmed | 11,008 | $291K | 1.8% | 2025-Q4 stale |
| UBS Group AG added | 156 | $4K | 0.0% | 2025-Q4 stale |
| RAYMOND JAMES FINANCIAL INC new | 128 | $3K | 0.0% | 2025-Q2 stale |
| CONCOURSE FINANCIAL GROUP SECURITIES, INC. new | 0 | — | 0.0% | 2025-Q2 stale |
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.