P. M. BRIEFING : Prime Prefers Offer by Whitney

Prime Computer Inc. announced today that its board prefers a tender offer by J. H. Whitney & Co. as “economically superior” to that of MAI Basic Four Inc. and postponed its annual meeting until Aug. 9.

Whitney and MAI Basic Four, based in Tustin, Calif., extended the deadlines for their competing offers to shareholders.

Prime management said its board of directors, the First Boston Corp. and Smith Barney, Harris Upham & Co. “unanimously determined that the pending tender offer by J. H. Whitney & Co. and its affiliates is economically superior to the MAI proposal.”

Prime, which is headquartered in Natick, had originally planned to hold a proxy vote among its stockholders today.

MAI, which has made an offer for the entire company valued by analysts at $945 million and a separate offer for Prime’s minicomputer business valued at $600 million, extended its offer to midnight Thursday.

J. H. Whitney, which made an offer last month for the entire company valued at $1.25 billion, extended its acceptance deadline of midnight Thursday to midnight Friday.