Ownership Summary
Quantumsphere Acquisition Corp (NASDAQ:QUMSU) has 8 institutional investors with active 13F positions as of March 2026.
- These investors held 5.4% of outstanding shares in March 2026, down from 13.4% in December 2025.
- They increased total shares held in QUMSU by 2.44% quarter over quarter, and investors in Quantumsphere Acquisition stayed flat from a year ago.
- Among the 8 funds, 3 bought more Quantumsphere Acquisition shares, 1 sold down, and 4 held their ground.
- The aggregate institutional position in Quantumsphere Acquisition amounted to 288.28K shares as of March 2026, up by 6.87K shares quarter on quarter, and with no net change year over year.
- Westchester Capital Management, LLC holds the largest position in QUMSU at 100.0K shares as of March 31, 2026, or 1.87% of shares outstanding.
- The largest buyers of Quantumsphere Acquisition for the quarter ending March 2026 were Clear Street Group Inc. (7.59K), GLAZER CAPITAL, LLC (219), UBS Group AG (5).
- The largest sales of QUMSU for the quarter ending March 2026 came from HRT FINANCIAL LP (951).
- Per Business Quant, the top 8 investors in QUMSU for the quarter ending March 2026 include Westchester Capital Management, LLC (100.0K), GABELLI & Co INVESTMENT ADVISERS, INC. (67.7K), GABELLI FUNDS LLC (57.3K), HRT FINANCIAL LP (30.14K), Clear Street Group Inc. (22.46K), Jpmorgan Chase & Co (10.0K), UBS Group AG (464), GLAZER CAPITAL, LLC (219).