ATRA Atara Biotherapeutics, Inc. Insider Trading

Director James Huang sells 313,446 shares of ATRA at $10.10; stock now $8.34, -53.9% from 52-week high. Contrasts with 2 prior well-timed buys at this ticker.

James Huang, a Director, sold 313,446 shares at $10.10 on 2026-05-07, reducing his holdings by 23.7% from 1,324,446 to 1,011,000 shares. This sale occurred when the stock was trading significantly above its current price of $8.34, which is now -53.9% from the 52-week high of $18.09. Notably, Huang's prior trading history at ATRA shows two well-timed buy transactions (2025-08-15 and 2025-07-17), both of which yielded positive 90-day returns (+9.0% and +57.4% respectively), establishing a pattern of sound entry timing at this specific ticker. The current price decline relative to the sale price, combined with his proven ability to identify opportune entry points at ATRA, raises questions about whether this sell was discretionary or driven by non-discretionary factors, and whether the subsequent 30-day +66.5% and 90-day +70.9% gains (from the current perspective) represent a significant misstep in exit timing.

10% owner Ecor1 Capital acquires over 500k shares of ATRA at $9.35 amid stock trading well below 52-week highs.

Ecor1 Capital, a significant institutional investor holding over 10% of Atara Biotherapeutics, purchased over half a million shares in a single open-market transaction, materially increasing its stake in the company. The purchase occurred while the stock trades at a substantial discount to its 52-week high, reflecting a meaningful pullback in valuation. Notably, this represents Ecor1 Capital's 43rd open-market purchase in the past three years, demonstrating a consistent pattern of buying on weakness rather than a one-off speculative trade. The company itself remains profitable with solid fundamentals, trading at an undemanding multiple despite near-term headwinds that may be driving the depressed share price. Institutional investors of this scale typically make portfolio decisions based on risk-reward positioning rather than insider knowledge of confidential developments, so this accumulation should be read as a calculation that current prices represent value—but the large outlay and frequency of prior purchases warrant monitoring to ensure the thesis continues to hold.

Director James Huang purchases 55,000 shares of ATRA at $12.19; holdings rise to 1,405,000 shares

Director James Huang purchased 55,000 shares on 2025-08-15 at $12.19 per share, increasing his holdings from 1,350,000 shares to 1,405,000 shares—a net addition of 55,000 shares representing a 4.1% increase to his pre-transaction position. The transaction totaled $670,422.50. This purchase represents a material commitment of capital by a director and reflects a decision to expand his equity stake in the company at the prevailing market price.

Director James Huang purchased 19,335 shares of ATRA at $9.64, raising holdings to 1,350,000 shares

James Huang, a director at Atara Biotherapeutics, purchased 19,335 shares at $9.64 on 2025-07-17 for a total value of $186,372.00, increasing his holdings from 1,330,665 shares to 1,350,000 shares. The purchase represents a 1.5% increase relative to his pre-transaction holdings, a modest addition to an already substantial directorship position. This transaction reflects an incremental commitment to the company, though the relatively small scale of the acquisition relative to his existing 1.33M share base suggests a measured rather than aggressive positioning.