NEW YORK, DEC. 21 -- The stock market kept its yearend rally going today with a spotty advance in quiet trading.

The Dow Jones average of 30 industrials rose 15.08 to 1990.38, extending its gain since Dec. 4 to 223.74 points. The last time the average closed above 2000 was Nov. 2, when it stood at 2014.09.

Advancing issues outnumbered declines by about 9 to 7 on the New York Stock Exchange. Big Board volume totaled 161.79 million shares, down from 276.22 million in the previous session.

Analysts said confidence among investors has been recovering gradually as stock prices have advanced this month, fueled partly by hopes that the broad economy might escape any severe damage from the market's steep fall in October.

The analysts 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.

For another, many traders seem to be seeking bargains in stocks depressed by yearend tax selling.

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

Wall Street has been busy lately studying the so-called "January effect" -- a historical tendency for stocks, especially smaller and deeply depressed ones, to rally early in a new year after the pressure of tax selling has lifted.

The phenomenon has received so much attention that some analysts fear it won't work out that way this time. Said Edward Nicoski, an analyst at Piper, Jaffray & Hopwood Inc., "The market is a discounting mechanism, and it will always do whatever it needs to do in order to confound and frustrate the majority of investors."

Pennzoil fell 1 7/8 to 77 1/2 and Texaco was down 1 at 37 1/2. Brokers said some traders who bought the stocks in anticipation of an agreement between the two companies to settle their long legal dispute sold when the news became official.

Singer dropped 5 1/2 to 43 1/2. The company said talks with various parties, including investor Paul Bilzerian, haven't produced any takeover proposals that it considers acceptable.

The NYSE's composite index of all its listed common stocks added 0.34 to close at 139.49.

Nationwide turnover in NYSE-listed issues, including trades in those stocks on regional exchanges and in the over-the-counter market, totaled 189.56 million shares.

Standard & Poor's index of 400 industrials gained 0.67 to 288.23. S&P's 500-stock composite index was up .38 at 249.54.