Mesa and Minstar reached an option agreement.

Under the agreement, Mesa Limited Partnership will acquire the 5 million shares of Pioneer Corp. held by a group headed by investor Irwin L. Jacobs. Mesa is attempting to complete a merger with Pioneer, which also had been sought by Jacobs’ Minneapolis-based holding company, Minstar Inc., and other investors referred to as the Minstar Group. Mesa obtained the option to purchase the shares at $21 each and is paying $4 per share for the option. The Minstar Group agreed that it will not acquire additional shares of Pioneer common stock and agreed to vote the shares that it holds in favor of the Mesa acquisition if the majority of the other voting Pioneer shareholders give their approval to the buy-out.