U.S. Steel said yesterday that its offer to pay $125 a share for 51 percent of Marathon Oil's stock has been "substantially oversubscribed," with more than the required 30 million shares of stock tendered.

Neither U.S. Steel nor Mobil Corp., also seeking control of Marathon, can purchase any Marathon shares until court challenges are decided.

U.S. Steel said information on the precise number of shares offered by Marathon stockholders is being compiled.

The U.S. Steel offer was made in an agreement with Marathon designed to thwart Mobil, which originally offered a $5.1 billion package calling for $85 a share in cash for 51 percent of Marathon and bonds in exchange for additional stock.

After U.S. Steel made its $6.25 billion offer, including bonds for any shares beyond the 51 percent level, Mobil boosted its cash price to $126 a share and total offer to $6.5 billion.

Midnight last Friday was the point at which shares had to be tendered to qualify for the higher cash price rather than the bond-for-stock swaps.

Shareholders still may withdraw stock tendered to Mobil or U.S. Steel, so some shares could jump to Mobil if it makes another offer. The deadline for withdrawal of shares tendered to either company depends on when a federal court in Columbus, Ohio, rules on a Mobil challenge to the U.S. Steel-Marathon pact.