Ace hedge fund manager Cathie Wood’s ARK Invest ETFs (exchange-traded funds) executed several notable trades on Tuesday, September 9, 2025. The moves highlight ARK’s continued conviction in biotech names, Prime Medicine (PRME) and Twist Bioscience (TWST), while trimming positions in Tempus (TEM), an AI-driven health-tech company.
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Wood Boosts Stake in PRME and TWST Stocks
Cathie Wood’s ARK Invest was an active buyer of biotech names on Tuesday. The flagship ARK Genomic Revolution ETF (ARKG) purchased about 157,000 shares of Prime Medicine, a gene-editing company, valued at roughly $620,000.
In addition, Wood added to TWST, a synthetic biology company that has been a frequent target in recent ARK trades. ARK bought $1.1 million worth of TWST through the ARK Innovation ETF (ARKK) and another $137,400 through ARKG, for a combined total of about $1.24 million.
In all, ARK invested nearly $1.86 million in biotech stocks on September 9, reflecting Wood’s continued conviction in the sector. Notably, PRME stock has gained 41% year-to-date, while TWST stock has fallen 46%.
Wood Trims Stakes in Tempus
On the sell side, ARK scaled back holdings in Tempus AI, a health-tech company known for its precision medicine platform. The funds sold a total of 25,936 shares across the ARKK and the ARKG ETFs, amounting to about $2.08 million.
Tempus has been one of ARK’s newer additions, but the partial trim suggests Wood is reducing exposure to select tech names while reallocating capital to other high-conviction areas.
In terms of share price, TEM stock has surged 140% year-to-date, highlighting the strong run that may have prompted profit-taking.
Let’s take a brief look at how all these stocks perform on TipRanks’ Stock Comparison Tool:
