Dow Has Biggest Fall Since July 15

Stock prices were pounded Thursday in the biggest one-day drop for blue-chips since a July rout. Nervous investors opted to book profits even after fresh indications that the economy is growing moderately and inflation is in check.

The Dow Jones industrial average fell 98.81 points to close at 6,303.71, the biggest one-day point loss since the 161.05-point plunge July 15 at the depths of a selloff.

The index of 30 blue-chip stocks has now fallen 3.7 percent, or 244 points, since reaching a record 6,547.79 on Nov. 25. But the Dow still is up more than 23 percent since the year began.

Stocks started the day higher, with the Dow up as much as 34 points, after three encouraging economic reports, but the rally was over in the first hour.

Declining issues led advancers by 4 to 3 on the New York Stock Exchange. Volume was heavy at 492.76 million shares as of 4 p.m., up slightly from Wednesday’s 494.19 million shares.

Some of the stocks that moved substantially or traded heavily Thursday:

NYSE

Micron Technology Inc. rose 3/8 to 36-3/8.

The company said Wednesday that its fiscal first-quarter revenues would be “up slightly” from the fourth quarter.

Iomega Corp. fell 2-1/4 to 19-7/8.

J.P. Morgan Securities trimmed its fourth-quarter earnings estimate to 17 cents a share from 19 cents but kept its buy rating for the company and its 1997 earnings projection of 82 cents a share. Iomega’s main product is the Zip drive, a removable storage drive for personal computers that is primarily targeted at the consumer PC market.

Warner-Lambert Co. rose 7/8 to 76-1/4.

Smith Barney upgraded the stock to buy from outperform. On Wednesday, a Food and Drug Administration advisory committee recommended approval of troglitazone, the company’s diabetes drug.

McDonalds Corp. fell 1-1/8 to 45-5/8.

Dean Witter lowered its 1996 and 1997 earnings estimates for the fast food company. Dean Witter said McDonalds told analysts late Wednesday that its comparable-store sales were off for November and December.

NASDAQ

Boston Technology Inc. rose 4-3/8 to 23-3/8.

The company agreed to provide Southwestern Bell with more than $60 million of hardware, software and services for enhanced telecommunications services over a three-year period.