NEW YORK, FEB. 11 -- Sears, Roebuck and Co. said today it was eliminating another 9,000 jobs, a nearly 50 percent increase over previously announced layoffs that are part of a campaign by the company to become more competitive.

The nation's biggest retailer also announced a 37 percent drop in 1990 fourth-quarter earnings, largely because of $155.2 million in costs associated with the restructuring of its work force.

Sears announced the actions as its board began a two-day meeting that was expected to take a hard look at the flagging retailing business and search for a way to regain lost customers and profits.

The 9,000 largely administrative jobs to be eliminated by the end of this year come on top of the 21,000 positions the Chicago-based company already is slashing from the staffs of Sears stores.

Sears Chairman Edward A. Brennan said the steps taken at Sears Merchandise Group would make the retailing business more competitive. Last year, Brennan took control of the merchandise group from Michael Bozic. The company announced today that Bozic, who has served as president to the merchandise group, has resigned and that his post would not be filled.

The company said it earned $378.8 million ($1.10 a share), down from $602.1 million ($1.76) in the final quarter of 1989.

Revenue rose to $15.56 billion from $15.18 billion. The merchandise group accounted for about 57 percent of that figure.

The company's results include those of its Allstate insurance business, Dean Witter Reynolds brokerage subsidiary, Coldwell Bankers Real Estate Group and Discover credit card operations. Sears said higher claim payouts at Allstate and a slumping real estate market also affected its earnings.

For all of 1990, Sears said it earned $902.2 million ($2.63), down from $1.51 billion ($4.30) in 1989.

Revenue rose to $55.97 billion from $53.79 billion a year earlier.

Sears stores have been losing business for years to discounters such as Wal-Mart Stores Inc., which offers consumers lower prices, and specialty retailers such as Limited Inc. and Home Depot Inc., which carry wider selections of merchandise.

During 1990, Sears managed only a 0.6 percent increase in retail sales over 1989 for its stores open at least a year. Meanwhile, Wal-Mart -- which is expected to overtake Sears this year as the nation's largest retailer -- had a 10 percent gain.

Sears also faces the industry-wide problem of consumers reluctant to shop because of the recession and the Gulf War.

Even with the steps announced today, the company's directors have their work cut out for them.

There has been speculation the board would decide to sell or close Sears's catalogue, a cornerstone on which the 104-year-old retailer was built. Sears has denied the speculation.

The latest job cuts include 1,400 in the company's catalogue operations. Sears said they resulted in part from the conversion of more than 230 Sears-owned catalogue sales offices to independently owned and operated businesses.

Eliminating Sears's catalogue would not fix all of the company's problems because the distribution system for that operation and the company's stores overlap.

Janet Mangano, an analyst with Jesup, Josephthal & Co. Inc., said, "The problems are not easily soluble. Even once a particular tack is selected, it's going to take a long time to turn it around."

Whatever action the board decides on, it likely will be viewed with some skepticism. Sears has tried a series of fixes for its troubles in recent years, but with little or no effect.

Its biggest rivals as general merchandisers, J.C. Penney Co. Inc. and Montgomery Ward & Co., began revamping their businesses in the mid-1980s to compete more effectively.

In 1988, Sears realigned its retailing management, hoping fewer layers would increase efficiency and reduce costs. In 1989, it made the switch to "everyday low prices," years after other retailers had adopted the policy.