* Yahoo, Chipotle, Yum to report after the close
* Mylan shares up 9 pct after Teva bid
* Dow off 0.4 pct, S&P down 0.15 pct, Nasdaq up 0.4 pct (Updates to midday, adds comment, updates prices)
By Tanya Agrawal
April 21 (Reuters) - U.S. stocks ticked lower on Tuesday, with the Dow industrials weighed by companies reporting earnings while the Nasdaq gained on the back of a proposed merger in the biotech sector.
Travelers, DuPont and IBM weighed the most on the Dow industrials. DuPont reported lower sales in all of its businesses and said a strong dollar would take a toll on its full-year earnings. IBM also mentioned currency effects when it reported a fall in revenue late on Monday.
Dupont was down 2.6 percent at $70.92 and IBM fell 1 percent to $164.41.
"I think the market has just written off the first-half of the year," said Aaron Jett, vice president of global equity research at Bel Air Investment Advisors in Los Angeles.
"We're just waiting for the dust to settle with the strong dollar and the oil prices and nobody really knows what the effects will be."
The dollar is up almost 9 percent since the beginning of the year against a basket of major currencies. A strong dollar hurts companies with large overseas operations.
Other companies such as United Technologies and advertising giant Omnicom also blamed the strong dollar for cutting their forecasts. United Technologies was up 0.3 percent at $116.96, while Omnicom was down 1.5 pct at $76.69.
At 11:48 a.m. EDT (1548 GMT) the Dow Jones industrial average was down 76.18 points, or 0.42 percent, at 17,958.75 and the S&P 500 was down 3.25 points, or 0.15 percent, at 2,097.15, while the Nasdaq Composite was up 20.46 points, or 0.41 percent, at 5,015.06.
Mylan rose as much as 9.4 percent to a record high of $74.44 after Israeli drugmaker Teva made an unsolicited offer of $82 per share, in what could be the drug industry's largest takeover this year. Teva rose 2 percent to $64.57. The Nasdaq Biotech index rose 1.9 percent.
Just 42.2 percent of the S&P 500 components that have reported earnings so far have beaten revenue estimates, compared with the 58 percent average top-line beat over the last year.
Almost 73 percent have beat bottom-line expectations, according to Thomson Reuters data.
Travelers reported a 21 percent fall in quarterly net profit and its shares fell 2.8 percent to $103.13.
Dow component Verizon was down 0.8 percent at $49 after its revenue fell short of expectations.
Earnings expected later on Tuesday include Chipotle, Yahoo and Yum Brands.
Advancing issues outnumbered declining ones on the NYSE by 1,492 to 1,416, for a 1.05-to-1 ratio on the upside; on the Nasdaq, 1,424 issues rose and 1,181 fell for a 1.21-to-1 ratio favoring advancers.
The benchmark S&P 500 index was posting 9 new 52-week highs and no new lows; the Nasdaq Composite was recording 77 new highs and 19 new lows. (Reporting by Tanya Agrawal; Editing by Savio D'Souza)