Fairmount Funds Management LLC: ZENAS BIOPHARMA INC (ZBIO): Quarterly 13F Position History
As of Q1 2026, Fairmount Funds Management LLC reported 2,359,025 shares of ZENAS BIOPHARMA INC (ZBIO), worth $46.1M and representing 3.3% of its 13F equity book. Quarter-over-quarter share count change: + 150,000 (+6.8%) . The position first appeared in Q3 2024 and has been disclosed across 7 13F-HR filings in Pactolio's tracked window.
- 2,359,025Shares Held (Latest Filing)
- $46.1MReported Market Value (Latest Filing)
- 3.3%Portfolio Weight (% of 13F Equity Book)
- +150,000Quarter-over-Quarter Share Change
- -$34.1MQuarter-over-Quarter Value Change
- 2,359,025Peak Reported Shares (Historical)
Quarterly 13F-HR Disclosure History Source: SEC 13F-HR filings, 7 quarter s
| Quarter | Shares | QoQ Share Change | Share Change (%) | Market Value | Weight | Implied Price |
|---|---|---|---|---|---|---|
| Q1 2026 | 2,359,025 | +150,000 | +6.8% | $46.1M | 3.3% | $19.6 |
| Q4 2025 | 2,209,025 | +316,219 | +16.7% | $80.2M | 6.1% | $36.3 |
| Q3 2025 | 1,892,806 | 0 | — | $42.0M | 3.8% | $22.2 |
| Q2 2025 | 1,892,806 | 0 | — | $18.3M | 2.4% | $9.7 |
| Q1 2025 | 1,892,806 | 0 | — | $15.0M | 2.3% | $7.9 |
| Q4 2024 | 1,892,806 | 0 | — | $15.5M | 1.5% | $8.2 |
| Q3 2024 | 1,892,806 | — | — | $32.0M | 2.6% | $16.9 |
Methodology & FAQ
How This Position History Is Sourced
Each row is one SEC Form 13F-HR filing disclosing this position. Share count, market value, and reported quarter are taken verbatim from the filing; portfolio weight is recomputed against the same filing's total reported equity book. Implied price-per-share is market value divided by shares — a quarter-end mark, not the manager's cost basis. See the full methodology document for the normalization rules.
When did Fairmount Funds Management LLC first disclose a ZBIO position in 13F-HR filings?
Fairmount Funds Management LLC first reported ZENAS BIOPHARMA INC (ZBIO) on its 13F-HR filing for the period ending 2024-09-30 (Q3 2024). The position has appeared on 7 reported quarters within Pactolio's tracked window.
What was Fairmount Funds Management LLC's most recent quarter-over-quarter share-count change in ZBIO?
Between Q4 2025 and Q1 2026, Fairmount Funds Management LLC added 150,000 shares of ZBIO (+6.8%), bringing the total reported position to 2,359,025 shares at a market value of $46.1M.
Does the implied price-per-share represent Fairmount Funds Management LLC's cost basis in ZBIO?
No. The implied price-per-share column is the 13F-HR reported market value divided by reported share count on the filing date (end of quarter). It is a quarter-end mark, not a cost basis or transaction price. Use it as a sanity check on the value column, not as an indicator of the manager's entry or exit price.