Christopher James Frankenfield - 31 Dec 2025 Form 4 Insider Report for Xilio Therapeutics, Inc. (XLO)

Role
Chief Financial Officer
Signature
/s/ Kevin Brennan, Attorney-in-Fact
Issuer symbol
XLO
Transactions as of
31 Dec 2025
Net transactions value
-$4,522
Form type
4
Filing time
05 Jan 2026, 16:30:21 UTC
Previous filing
25 Nov 2025
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Frankenfield Christopher James Chief Financial Officer 828 WINTER STREET, SUITE 300, WALTHAM /s/ Kevin Brennan, Attorney-in-Fact 05 Jan 2026 0001988344

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction XLO Common Stock Options Exercise +19,375 +156% 31,796 01 Jan 2026 Direct F1
transaction XLO Common Stock Sale $4,522 -7,030 -22% $0.6432 24,766 02 Jan 2026 Direct F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction XLO Stock Option (right to buy) Award $0 +668,789 $0.000000 668,789 31 Dec 2025 Common Stock 668,789 $0.8410 Direct F3, F4, F5
transaction XLO Restricted Stock Units Options Exercise $0 -19,375 -33% $0.000000 38,750 01 Jan 2026 Common Stock 19,375 Direct F1, F6
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

Transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Explanation of Responses:

Id Content
F1 Restricted stock units ("RSUs") convert to stock on a one-for-one basis.
F2 The reported sale of 7,030 shares occurred automatically in a "sell to cover" transaction pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on April 8, 2024 solely to cover tax withholding obligations in connection with the vesting of restricted stock units.
F3 On October 8, 2025, the Board of Directors (the "Board") approved the adoption of the Xilio Therapeutics, Inc. 2025 Stock Incentive Plan (the "2025 Plan"), subject to stockholder approval of the adoption of the 2025 Plan. On October 8, 2025, the Compensation Committee of the Board granted these options (referred to as "Tranche 3 Options" in the 2025 Plan) to the Reporting Person, subject to stockholder approval of the adoption of the 2025 Plan. The stockholders approved the adoption of the 2025 Plan on November 21, 2025. On December 31, 2025, the performance criteria for a portion of the Tranche 3 Options was met.
F4 The portion of Tranche 3 Options that achieved the vesting condition is equal to the percentage of the Series B Warrants exercised and/or cancelled due to the receipt by Xilio Therapeutics, Inc. of Non-Dilutive Capital (as defined in the Series B Warrants) by December 31, 2025.
F5 This option vests in three (3) equal annual installments over the three-year period beginning on December 31, 2025, subject to the Reporting Person's continued service to the registrant through each applicable vesting date.
F6 These RSUs were granted on January 1, 2024 and vest in four equal annual installments beginning on January 1, 2025.