Mesirow Financial Investment Management, Inc.
SEC Form 13F institutional filer · CIK 0001469475
13F-HR · 254 reported holdings · 2026-03-31
SEC-registered institutional investment manager.
Reported long-US-equity value
$4.52B
Top-10 concentration
56.5%
Mesirow Financial Investment Management, Inc. — $4.52B AUM allocation strategy
Mesirow Financial Investment Management, Inc. files SEC Form 13F and reports $4.52B of long US equity value across 254 reported holdings for 2026-03-31.
Its largest sector bet is Financials 16.3%, followed by Information Technology 10.3% and Communication Services 5.8%.
The top 10 holdings account for 57% of reported value — a conviction-weighted book concentrated in its best ideas. The sector and industry splits below are of the same reported value. Track quarter-over-quarter adds, trims, new positions and exits below — sourced from SEC 13F filings, public domain.
Mesirow Financial Investment Management, Inc. — latest SEC 13F insights
Reported long-US-equity value (13F AUM)
$4.52B
total across 254 reported holdings · 2026-03-31 · excludes shorts, cash, non-US
Top-10 concentration
57% of value
higher = narrower conviction; lower = spread / hedging
Biggest adds (shares)
+$IVV +2.67M sh · +$280M+$IWM +1.11M sh · +$129M+$TROW +624K sh · +$19.8M
Biggest trims (shares)
−$FITB −53.3K sh · −$2.66M−$AAPL −24.8K sh · −$24.4M−$DOW −8.28K sh · +$20.3K
Exited to nil (held last quarter, gone now)
$VEEV ($281K last qtr)$VLO ($278K last qtr)$PYPL ($260K last qtr)$KEYS ($252K last qtr)$ZBH ($232K last qtr)
Sector allocation (share of reported value)
each slice is a share of the reported long-US-equity value — smaller sectors and the rest of the book roll into “Other holdings”
Qtr shift = share-point change vs the prior quarter's filing — first period tracked for this filer; the column fills in with the next quarterly refresh.
Industry allocation (share of reported value)
- Multi-Sector Holdings10.4%—
- Interactive Media & Services5.8%—
- Technology Hardware, Storage & Peripherals5.5%—
- Systems Software3.7%—
- Asset Management & Custody Banks2.2%—
- Diversified Banks2.0%—
- Broadline Retail1.9%—
- Financial Exchanges & Data1.7%—
- Other holdings66.9%—
the finer GICS cut of the same book — same denominator — smaller industries roll into “Other holdings”
Qtr shift = share-point change vs the prior quarter's filing — first period tracked for this filer; the column fills in with the next quarterly refresh.
Top S&P 500 holdings
7 of 7 rows · sorted by Value ↓
| Ticker | Holding | Shares | Value | Δ QoQ | Weight |
|---|---|---|---|---|---|
| $BRK.B | Berkshire Hathaway Inc.-Class B | 977K | $468M | +164K | 10.4% |
| $AAPL | Apple Inc | 975K | $247M | -24.8K | 5.5% |
| $MSFT | Microsoft Corporation | 457K | $169M | +167K | 3.7% |
| $GOOGL | Alphabet Inc | 543K | $156M | +19.5K | 3.4% |
| $GOOG | Alphabet Inc. Class C Capital Stock | 373K | $107M | +12K | 2.4% |
| $JPM | JP Morgan Chase & Co | 312K | $91.8M | +16.9K | 2.0% |
| $AMZN | Amazon.com Inc | 408K | $84.9M | +63.3K | 1.9% |
…and 247 more holdings in the full 13F filing (top positions only shown).
SEC Form 13F data sets · public domain · 45-day filing lag · >$100M AUM managers · as reported
← All 13F filers·← QuantOrb.pro
How to read Δ QoQ — the five insight categories, and the caveats
The categories. Analysts, quants and retail traders look past total portfolio value to isolate actionable signals. Five categories matter.
Conviction & concentration shifts
New positions vs complete exits — a brand-new stock signals high conviction; a full liquidation suggests a broken thesis or tax-loss harvesting. Aggressive sizing — look at share count, not dollars: a 20% share increase during a drawdown is strong dip-buying. Concentration — a narrowing top-5/10 means conviction; spreading capital across more names means hedging.
Sector & macro allocation rotations
Aggregating Δ QoQ moves across sectors shows where smart money is leaning in or sneaking out — rotating out of growth into defensives or energy, for example. The fund's total long equity exposure quarter-over-quarter is a proxy for overall institutional risk appetite.
Crowding & smart-money consensus
When several managers initiate or expand the same stock in the same quarter, that is institutional consensus. Contrarian reads: top pickers buying hard into a beaten-down name the market is selling.
Derivative & option overlays
Reported call/put changes indicate whether managers are adding downside hedges or leveraging upside exposure. Note: a long increase may be half of a market-neutral pair trade.
Who reads this
| Retail "cloners" | High-conviction ideas to replicate ~45 days after quarter-end. |
| Corporate IR | Which funds bought or dumped the stock, before the next call. |
| Quant / algo traders | Cross-sectional factor inputs: flow, momentum, ownership. |
Four caveats before you trade on it
- 45-day lag — holdings are quarter-end; positions may already be closed.
- Long-only — 13Fs miss shorts, pair trades and cash.
- No non-US / fixed income — the picture is US equities plus options.
- Corporate actions — splits and spinoffs distort raw share deltas.
Newsletter signup
Free subscription. Daily trading day morning dispatch. No spam.