Antitrust Claim Reduction Act of 1991

Antitrust Claim Reduction Act of 1991 - Amends the Clayton Act to require the court to reduce a claim under such Act of any claimant releasing any person from liability or potential liability for such claim by the greatest of: (1) any amount stipulated for such purpose; (2) the consideration paid for the release; or (3) the actual damages fairly allocable to the person being released from liability or potential liability (or treble such actual damages to the extent such claim is for treble damages) and any interest on such actual damages.

Directs the court to presume conclusively that any person whose sales or purchases would otherwise be included in a calculation of damages based on overcharges or underpayments has been released from liability or potential liability if it has not been joined as a defendant and if it is established by the defendant that such person is legally and practically available as a party to the action to recover such damages.

Specifies that: (1) where the claim is based upon a price-fixing agreement among competitors and damages are sustained by reason of overcharges or underpayments resulting from such agreement, damages shall be allocated on the basis of each such competitor's proportionate share of the total of overcharges or underpayments; and (2) with respect to all other claims, damages shall be allocated on the basis of relative responsibility for the origination or perpetration of the violation for which damages are being awarded, with exceptions.