NEW YORK, JUNE 18 -- The stock market nudged the Dow Jones average of 30 industrials to another record high today, after spending most of the session in the losing column amid worries about the quarterly "triple witching hour."

The closely watched index closed at 2408.13, up 0.78 points from Wednesday's close, which had remained unchanged at Tuesday's previous record-breaking level of 2407.35.

Volume at the New York Stock Exchange came to 168.58 million shares. Gainers slightly outnumbered losers among Big Board-listed issues.

Analysts said many traders had moved to the sidelines to avoid being caught up in possible market swings at the quarterly expiration of stock options, stock index futures and index options.

Under new rules being enacted this week, trading in some of the futures contracts ended today, with Friday's opening prices to be used for settlement.

The rules were designed to curb volatility. But analysts said the market was jittery because there was no way to know the effectiveness of the new rules.

As a result, "there just was a lack of activity and direction," said Edward P. Nicoski, a technical analyst at Piper Jaffray & Hopwood Inc. in Minneapolis.

"I think there was a fear of unraveling trading programs in the triple witching program tomorrow {Friday}," he added.

For most of the day, the Dow Jones industrial average generally hovered 5 to 6 points lower, with losing issues outnumbering gainers by a small margin.

Only in the last hour did the index move into the plus column, as a few computerized programs kicked in, analysts said.

Gillette led the New York Stock Exchange's list of most-active issues at 40 1/4, up 3 1/4, on word that Revlon had offered at least $40.50 per share for the company. Revlon closed at 20, up 1/4.

Pan Am was up 1/2 at 6 1/8, after a report that New York developer Donald Trump had acquired a large position in the stock.

AT&T stood at 28 7/8, up 1 1/8, while IBM was down 1/2 at 160 7/8; Digital Equipment was up 3/4 at 167 1/2, and General Electric was up 1/4 at 53 1/2.

Southland was up 3 at 67; CMS Energy was down 1 to 18 1/2.

Among oils, Chevron was up 1/8 at 59 3/4; Exxon was up 1/8 at 89 7/8, and Mobil was down 1/4 at 50 1/2.

Nationwide turnover in NYSE-listed issues, including trades in those stocks on regional exchanges and in the over-the-counter market, totaled 194.96 million shares.

The NYSE index was up 0.40 points at 171.84, a new record.

Standard & Poor's index of 400 industrials rose 1.00 to 354.22.