NEW YORK (AP) _ The stock market was little changed in slackened trading today, struggling to extend its yearend rally.

The Dow Jones average of 30 industrials, up 208.56 points over the past two weeks, rose 3.15 to 1,978.45 by 11 a.m. today on Wall Street.

But losers slightly outnumbered gainers in the overall tally of New York Stock Exchange-listed issues, with 679 up, 689 down and 431 unchanged.

Volume on the Big Board came to 58.79 million shares at midmorning.

Analysts said confidence among investors had been gradually recovering as stock prices advanced since early this month, based partly on hopes that the broad economy might escape any severe damage resulting from the crash in October.

They also cited some seasonal influences working in the market's favor. For one thing, money managers at investing institutions are presumed to be eager to bid up stocks to improve the results they show in yearend reports to clients.

For another, many traders are apparently seeking out ''bargains'' in stocks depressed by yearend tax selling.

Concern persists, however, that the market remains vulnerable to aftershocks from its historic selloff this fall.

Pennzoil fell 3 1/8 to 76 1/4 and Texaco was down 3/4 at 37 . Brokers said some traders who bought the stocks earlier on anticipation of an agreement between the two companies to settle their long legal dispute sold when the news became official.

The NYSE's composite index of all its listed common stocks edged up .06 to 139.21. On the American Stock Exchange, the market value index was down .04 at 256.06.