* GM, Boeing rise after strong results
* Valeant sinks after Citron report
* VMware, Yahoo down on poor results
* Dow up 0.26 pct, S&P up 0.06 pct, Nasdaq down 0.04 pct (Updates prices, adds details)
By Abhiram Nandakumar
Oct 21 (Reuters) - U.S. stocks were little changed on Wednesday as healthcare stocks resumed their slide for a second day, offsetting gains by General Motors and technology stocks.
The S&P 500's healthcare sector declined 1.08 percent, while the Nasdaq biotech index fell 1.5 percent.
Valeant Pharma's U.S.-listed shares sank 20.8 percent to $116.23, and were halted, after short-seller Citron Research released a critical report on the company.
Health insurers Aetna, Humana, Anthem and Cigna all fell about 4 percent after Democratic presidential candidate Hillary Clinton said she had "serious concerns" about the mergers the companies were proposing.
At 11:32 a.m. ET (1532 GMT), the Dow Jones industrial average was up 44.53 points, or 0.26 percent, at 17,261.64, the S&P 500 was up 1.26 points, or 0.06 percent, at 2,032.03 and the Nasdaq composite index was down 2.09 points, or 0.04 percent, at 4,878.89.
Investors focused on quarterly results by industry bellwethers this week, parsing the reports for comments on guidance and the measures the companies are taking to counter the impact of a global economic slowdown.
"During the course of the third quarter, we actually saw consensus estimates drop for both revenue and earnings," said Eric Weigand, senior portfolio manager at the Private Client Reserve at U.S. Bank.
"You could make the point that there is a low hurdle for companies to exceed on these diminished expectations."
Shares of General Motors rose 4.7 percent to $35.05 after the carmaker's quarterly profit beat estimates.
Boeing rose 0.8 percent to $139.86 after its results beat estimates.
Of the S&P 500 companies that have reported results so far, 40 percent have exceeded revenue estimates. About 60 percent typically beat estimates in a quarter, according to Thomson Reuters data.
S&P 500 companies are expected to report a 3.9 percent decline in third-quarter profit and a 3.8 percent fall in revenue.
American Express and eBay report after the close.
Twitter fell 6 percent to $29.04 after Morgan Stanley downgraded the stock to underweight, citing increased competition and limited scope for user growth.
KLA Tencor soared 23.3 percent to $66.42 after the semiconductor equipment maker agreed to be bought by Lam Research in a $10.6 billion deal. Lam rose 6.4 percent to $74.53.
Ferrari was up 9.8 percent at $57.11 in its debut on the New York Stock Exchange. Fiat, which owns 90 percent of Ferrari, fell 3.6 percent to $15.37.
VMware sank 18.2 percent to $56.31 after the virtualization software maker forecast current-quarter revenue below estimates.
Yahoo was down 4.2 percent at $31.46 after the Internet company's quarterly earnings and profit missed expectations.
Declining issues outnumbered advancing ones on the NYSE by 1,508 to 1,415. On the Nasdaq, 1,517 issues fell and 1,080 advanced.
The S&P 500 index showed 21 new 52-week highs and three new lows, while the Nasdaq recorded 46 new highs and 55 new lows. (Reporting by Abhiram Nandakumar in Bengaluru; Editing by Don Sebastian)