Atlas Venture Fund X, L.P. 4

What Happened

• Atlas Venture Fund X, L.P. (a >10% institutional holder) disposed of a total of 827,946 shares of Generation Bio common stock in connection with the company’s change of control/merger effective Feb 9, 2026. The disposition was part of the tender/merger consideration: $4.2913 cash per share (less any required tax withholding) plus one non-tradeable contingent value right (CVR) per share that entitles holders to potential additional cash payments (estimated maximum contingent amount $25.01 per CVR).

Key Details

• Transaction date: February 9, 2026 (effective time of the merger).
• Shares disposed: 711,193 + 116,693 + 60 = 827,946 shares (reported as dispositions in change of control, code “U”).
• Price reported on Form 4: N/A for each line (dispositions via merger); footnote discloses $4.2913 cash per share plus one CVR (CVR carries up to $25.01 contingent consideration).
• Shares remaining after transaction: The filing reports these shares as disposed in the merger (no continuing holdings reported for these disposed shares).
• Filing timeliness: Report filed 2026-02-09 for transactions on 2026-02-09 (timely).
• Ownership notes: Atlas Venture Fund X is the direct holder; related entities (general partners) disclaim beneficial ownership except for any pecuniary interest (see footnotes).

Context

• This was not an open-market sale by an executive but an institutional tender/merger disposition as part of XOMA Royalty’s acquisition of Generation Bio — the shares were exchanged for merger consideration (cash + CVR), not sold on the public market. The CVR is non-tradeable and its extra payment is contingent on future events, so total per-share consideration could be up to $4.2913 + $25.01 = $29.3013 only if contingent conditions are met.