MIDWAY AIRLINES <MDWY> SETS HOLDER RIGHTS PLAN Midway Airlines Inc, which has frequently been mentioned as an acquisition target, said it declared a shareholder rights plan. Holders will get a dividend of one preferred share purchase right on each outstanding share of common stock. Each right, when exercisable, will entitle the holder to purchase one one-hundredth share of Series C Junior Participating preferred stock for 50 dlrs. The rights are intended to assure that all holders receive fair treatment in the event of a takeover. The company said this is not in response to a known effort to acquire control. The rights will be exercisable 10 days after a person or group buys 20 pct of the company's common, or announces or commences a tender offer that would result in acquisition of 30 pct or more of its common. Midway can redeem the rights at two cts each at any time prior to expieration of 10 days after the acquisition by any person of 20 pct or more of the companyt's common, it said. If Midway is acquired, each right will entitle its hodler to purchase a number of the acquiring company's common shares having a market value at that time of twice the right's exercise price. The dividend will be payable to holders of record April six, and expire 10 years later on April 6, 1997.