Tech shares were heading for another rout in US trading early Tuesday amid worries about runaway equity valuations as Tesla plunged after it was left out of the S&P 500. About 35 minutes into trading, the Dow Jones Industrial Average had dropped 2.0 percent at 27,561.54. The broad-based S&P 500 also shed 2.0 percent to 3,357.28, while the tech-rich Nasdaq Composite Index lost 2.6 percent to 11,023.56. Stocks have been under pressure the last three sessions in the wake of a series of records for the S&P 500 and Nasdaq following huge gains in August. Analysts cited mounting US-China tensions and a stalemate in Washington over another round of stimulus funding as factors in the pullback, along with profit taking following earlier gains. The retreat has been led by highflying companies like Amazon, Apple and Facebook, all of which were down more than two percent in the first session following the Labor Day holiday on Monday. But the biggest loser was Tesla, which dove 16.9 percent, after the S&P 500 did not add the electric car company to its index late last week, disappointing investors who had acquired shares in anticipation of the move. "It was viewed as almost a consensus move based on all the metrics that Tesla was likely to get into the S&P 500 club this time around and thus will have a negative knee jerk investor reaction," Wedbush analyst Dan Ives said. "In a nutshell Tesla not getting into the S&P 500 will be a head scratcher to the bulls." Among other individual companies, electric truck company Nikola shot up 33.7 percent after announcing a partnership with General Motors. Under the partnership, GM will receive an 11 percent stake in the firm in exchange for providing technology and manufacturing. GM jumped 7.0 percent. jmb/hs