17 CFR §1.29

1. (a)The investment of customer funds in instruments described in § 1.25 shall not prevent the futures commission merchant or derivatives clearing organization so investing such funds from receiving and retaining as its own any incremental income or interest income resulting therefrom.
2. (b)The futures commission merchant or derivatives clearing organization, as applicable, shall bear sole responsibility for any losses resulting from the investment of customer funds in instruments described in § 1.25. No investment losses shall be borne or otherwise allocated to the customers of the futures commission merchant and, if customer funds are invested by a derivatives clearing organization in its discretion, to the futures commission merchant.