Bendix Corp. appears to have won the first round in its hostile $1.5 billion attempt to take over Martin Marietta Corp.

Bendix announced yesterday that about 20.6 million shares of Martin Marietta had been offered (tendered) by midnight Saturday. That is about 58 percent of the outstanding shares of the Bethesda-based aerospace company.

Bendix has said it will pay $43 cash each for 15.8 million shares, or about 45 percent, of Martin Marietta stock and said it plans to acquire the rest by exchange 0.82 shares of Bendix Corp. for each of the remaining shares. Bendix already owns 4.5 percent of Martin Marietta stock.

But Martin Marietta shareholders can withdraw those shares anytime before midnight Sept. 16.

In the meantime, Martin Marietta has its own counter-offer to buy slightly more than half of the outstanding shares of Bendix for $75 a share. To be assured of getting cash for some of their shares, Bendix owners must tender their stock to Martin Marietta by midnight Thursday. Martin Marietta apparently also has been searching for a friendly merger partner -- a White Knight in the parlance of takeover specialists.

The surprise Bendix offer for Martin Marietta has developed into the thorniest takeover fight this year. Martin Marietta has vowed to fight the takeover to the end. In addition to its counter-offer to buy Bendix, the company also has filed suit in Delaware to block the acquisition.

William M. Agee, chairman of Bendix -- a maker of auto parts, electronic equipment and machine tools based in Southfield, Mich. -- said "The results are a clear referendum by Martin Marietta shareholders in favor of the tender offer. Their shareholders have spoken decisively and positively with their action."

A spokesman for Martin Marietta called the results meaningless because the aerospace corporation's shareholders can take back their stock anytime in the next 10 days.

Analysts give Bendix, with $4.4 billion in sales the bigger of the two companies, the edge in the duel, but have raised the possibility that each company will end up ownning 50 percent of the other. In that case, the courts might have to untangle the situation.

Martin Marietta, with $3.3 billion in sales last year, is the area's biggest industrial company.

Sunday was the so-called pro-ration date in the Bendix offer to buy Martin Marietta shares. Because Bendix is not willing to pay cash for all of Martin Marietta's stock, a shareholder that wanted to be assured of getting cash for some of his or her shares had to offer to sell Saturday. If no one takes back the stock already tendered and Bendix makes no changes in its offer, Martin Marrieta shareholders who offered to sell to Bendix by Saturday will get $43 for about 77 percent of the stock tendered.

For example, if a shareholder offered Bendix 100 shares, he or she would get cash for 77 of them.

If the Bendix offer ultimately is successful, these shareholders will get 0.82 shares of Bendix stock (worth nearly $48 based on Bendix's $58.50 closing price last Friday) for the remaining each of the left over 23 shares. Shareholders who did not tender by Saturday would get only Bendix stock and no cash at all.