Is it over? After another day of heavy losses for stocks, dispirited investors -- who've watched the gains from Monday's rally fizzle all week -- wonder if they've seen the last days of the bull market. The negative catalysts du jour on Thursday were weak economic data, an SEC investigation of General Motors ( GM), and more uncertainty surrounding the Bush administration. The downdraft has now taken the major indices back to test five-month lows hit on Oct. 12 and 13. The Dow Jones Industrial Average finished down 115.03 points, or 1.11%, at 10,229.95. That leaves the index below its October closing low of 10,216, hit Oct 13. The Dow was pressured by GM, which slumped 6.8%, as well as declines in Johnson & Johnson ( JNJ) and Home Depot ( HD). The S&P 500 dropped 12.48 points, or 1.05%, to 1178.90. That's only two points about the broad index's Oct. 13 low close of 1176. Once again, energy shares took a beating, as a 75% jump in Exxon Mobil's ( XOM) earnings wasn't enough for the bulls. The Amex oil index finished down 2.3%, with Exxon Mobil losing 1.5% on the day. Crude oil prices, meanwhile, added 43 cents to $60.20 per barrel on the day. Tech stocks, which some hoped would lead the market after energy stepped aside, led to the downside. The Nasdaq Composite plunged 36.24 points, or 1.73%, to 2063.81. That's still a good way away from its Oct. 12 low of 2037. The tech-heavy index was weighed down by semiconductor issues. The Philadelphia semiconductor index dipped 2.7%, amid declines in shares of AMD ( AMD), Intel ( INTC) and Texas Instruments ( TXN) Breadth was horrendous, with declining issues topping advancing ones by nearly 3 to 1 on both the Nasdaq and the NYSE. The plunge that has led the major indices to five-month lows in the first part of October has created a lot of downward momentum that seems to be impossible to reverse, at least for now. Many investors, it seems, are more keen to sell into strength than to buy into weakness.