TANDEM DIABETES CARE INC (TNDM) Institutional Ownership Changes & 13F Activity

TANDEM DIABETES CARE INC (TNDM). Institutional ownership data tracks hedge funds, asset managers, and other institutional investors based on recent SEC Form 13F filings (Q1 2026). This page analyzes institutional buying and selling activity, new holdings, and sold-out positions in the latest reporting period. Notable filers include Wellington Management Group Llp, Morgan Stanley, Driehaus Capital Management Llc, Two Sigma Investments, Lp, and Marshall Wace, Llp.

InstitutionTypeChange in sharesChange Position %SharesReported stock balancePortfolio quarterFiling date
Op Asset Management LtdSell-15,279-89.3%1,835$35.18KQ1 2026Sep 28, 2026
Algert Global LlcBuy+8,860+8.1%117,799$2.26MQ1 2026Aug 11, 2026
Wells Fargo & Company/MnSell-52,881-62.6%31,530$604.43KQ1 2026Jul 08, 2026
Western Wealth Management, LlcBuy+140—140$2.68KQ1 2026May 19, 2026
Bank Of America CorpSell-329,279-46.9%373,224$7.15MQ1 2026May 18, 2026
California State Teachers Retirement SystemBuy+19,844+30.8%84,255$1.62MQ1 2026May 18, 2026
AmundiSell-16,830-57.2%12,615$241.83KQ1 2026May 18, 2026
Wellington Management Group LlpBuy+944,455+960.7%1,042,764$19.99MQ1 2026May 15, 2026
Morgan StanleySell-722,955-34.7%1,357,542$26.02MQ1 2026May 15, 2026
Driehaus Capital Management LlcBuy+694,072+43.1%2,304,414$44.18MQ1 2026May 15, 2026
Two Sigma Investments, LpBuy+662,667+55.2%1,864,194$35.74MQ1 2026May 15, 2026
Marshall Wace, LlpBuy+566,941+64.8%1,442,472$27.65MQ1 2026May 15, 2026
Goldman Sachs Group IncBuy+535,522+31.8%2,218,922$42.54MQ1 2026May 15, 2026
Barclays PlcSell-496,691-54.1%421,236$8.08MQ1 2026May 15, 2026
Holocene Advisors, LpBuy+460,941+2807.5%477,359$9.15MQ1 2026May 15, 2026
Point72 Asset Management, L.P.Buy+420,478—420,478$8.06MQ1 2026May 15, 2026
Quantinno Capital Management LpBuy+361,361+123.5%653,870$12.53MQ1 2026May 15, 2026
Sessa Capital Im, L.P.Sell-269,243-5.4%4,730,757$90.69MQ1 2026May 15, 2026
First Light Asset Management, LlcBuy+225,222+20.7%1,314,715$25.20MQ1 2026May 15, 2026
Arrowmark Colorado Holdings LlcBuy+213,918+7.4%3,103,609$59.50MQ1 2026May 15, 2026
Millennium Management LlcBuy+178,099+30.5%761,672$14.60MQ1 2026May 15, 2026
Alliancebernstein L.P.Sell-161,144-68.8%73,149$1.61MQ1 2026May 15, 2026
Toronto Dominion BankBuy+150,078—150,078$2.88MQ1 2026May 15, 2026
Trexquant Investment LpBuy+146,579+142.7%249,298$4.78MQ1 2026May 15, 2026
Susquehanna Portfolio Strategies, LlcBuy+139,741+210.3%206,193$3.95MQ1 2026May 15, 2026
Jacobs Levy Equity Management, IncSell-129,762-7.8%1,523,946$29.21MQ1 2026May 15, 2026
Freestone Grove Partners LpSell-112,094-7.8%1,330,742$25.51MQ1 2026May 15, 2026
Citadel Advisors LlcBuy+104,064+5.0%2,192,667$42.03MQ1 2026May 15, 2026
Verition Fund Management LlcBuy+96,532+911.8%107,119$2.05MQ1 2026May 15, 2026
D. E. Shaw & Co., Inc.Sell-70,360-8.2%783,906$15.03MQ1 2026May 15, 2026
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Frequently asked questions about TNDM activity

  • Which institutional owners are buying TNDM?

    Institutional owners buying TNDM include investors who have either initiated new positions or increased their existing holdings based on recent SEC 13F filings. The activity table above highlights which funds added shares in the latest reporting periods and how their positions changed over time.

  • What does "buy" mean in TNDM activity?

    "Buy" means an investor increased their reported position in TNDM compared to the prior reporting period. This reflects growing exposure to TANDEM DIABETES CARE INC (TNDM) rather than necessarily a brand-new position (though new positions also appear as buys when prior quantity was zero).

  • Is institutional interest in TNDM increasing?

    Institutional interest in TNDM can be assessed by comparing the number of tracked funds adding or increasing positions versus those trimming or exiting across the periods shown. A higher number of additions typically signals increasing participation among large filers, but it should be read alongside position sizes and the full table.

TNDM Institutional Ownership Changes and 13F Activity Q1 2026 | InsiderSet