LONDON: Technology companies and utilities, the pillars keeping the US bull market from collapsing, are trading near their most expensive valuations in at least three years. The last time the market was so dependent on computer-related companies and power producers was in the three months ended March 2000, just before the Standard & Poor’s 500 Index began a 2 1/2-year, 49% plunge, according to data compiled by Bloomberg.

“It’s a time to be careful,” said John Carey, who helps oversee about $82 billion in US assets at Pioneer Investment Management in Boston. Valuations for some technology companies and utilities “from a historical standpoint seem high.”

Technology in the S&P 500 traded at an average 29.1 times earnings this month, the most since 2004, weekly data compiled by Bloomberg show. Dividend yields paid by utilities are the smallest compared with the index in at least 12 years. While US stocks have climbed in the fourth quarter every year since 2000 and 73% of the time since the Great Depression, the S&P 500 would have a gain of just 0.3% this year without advances in technology stocks led by Google and Apple and utilities including Allegheny Energy, according to the data.

“Could we have a year-end rally? It certainly seems more difficult this time around,” said Alessandra Querini at Aletti Gestielle SGR in Milan, which oversees about $19 billion. Technology is responsible for 13% of this year’s S&P 500 advance. Since November 7, when Cisco Systems reported a ‘dramatic’ drop in sales to financial and automobile companies, the Nasdaq Composite Index retreated 4.4%, contributing to the biggest weekly decline since April 2002. The index gets 44% of its market value from computer-related shares.

Before San Jose, California-based Cisco’s announcement, technology and utilities were the only two of 10 industry groups in the S&P 500 to post increases since September. The index has lost 4.8% in the fourth quarter, dragged down by a 12% drop in financial shares.

The S&P 500 slid 3.7% last week to 1,453.70, paring its 2007 advance to 2.5%. December futures on the S&P 500 advanced 0.3% as of 10:29 a.m. in London. Equities outside the US were little changed this quarter through last week, with six of 10 industry groups in the Morgan Stanley Capital International EAFE Index posting advances. The index of developed markets excluding the US slipped 0.3%, with stocks of telephone companies, utilities, energy producers and household products makers advancing at least 3.6%.

Technology companies in the MSCI EAFE today lost 1.7%, while utilities dropped 1.5%. Google, owner of the world’s most-used internet search engine, and Apple, maker of the iPod music player, may be the biggest reasons why the stock market is still ahead for the year. Google rose above $700 for the first time last month after the company said third-quarter profit rose 46%.