WILMINGTON, Del. -- DuPont Co., the biggest U.S. chemicals company, said yesterday that it will issue a new class of stock to track the performance of its life sciences business and expand the unit through alliances and acquisitions.

The company said it is discussing alliances with unspecified pharmaceutical companies to build up its relatively small drug business this year, and is looking to expand in other life sciences including agriculture, biotechnology and nutrition.

The plan comes about a year after DuPont said it would increase its focus on life sciences, which are generally faster-growing than its traditional chemicals businesses.

The new class of DuPont life sciences tracking stock could be expected to trade at higher multiples of estimated future profit than its existing shares, making it more useful as currency to pay for mergers and joint ventures, analysts said.

"It should give them some flexibility, and I expect them to use it for acquisitions" and positions in other companies, said Bill Fiala, an analyst at Edward Jones.

Life sciences contributed about $4.3 billion to DuPont's $24.8 billion in sales last year, though after charges the unit posted a loss.

Investors applauded the move as a signal that DuPont was following through on its life sciences strategy. Shares rose $3.8125 to close at $57.375 yesterday for the largest percentage gain since the company said May 11 that it would spin off part of its Conoco Inc. energy unit.

A person close to Monsanto Co. who is familiar with the matter said last week that the company was in preliminary talks with DuPont about a business combination.

"These are bold management moves, and it will change the way investors look at DuPont's stock," said Frank Mitsch, an analyst at Deutsche Bank Securities.

Wilmington, Del.-based DuPont said it expects to file to sell the tracking stock no sooner than the end of this year, and that the move will then be subject to shareholder approval.

With the introduction of a tracking stock, DuPont may have hit on the solution to its the biggest obstacle to an alliance with a drugmaker, an analyst said.

Still largely a chemicals maker, DuPont's stock sells for about 21 times its estimated 1999 per-share profit, while shares of drugmakers can sell for more than 50 times their estimated per-share profit.

Pub Date: 3/11/99