US STOCKS-Wall St to rise on earnings, data weighs
* Windstream rallies; set to spin off assets into REIT
* Pfizer, Merck rise as results beat expectations
* Herbalife shares tumble after it cuts sales outlook
* Futures up: Dow 40 pts, S&P 3 pts, Nasdaq 7 pts (Updates prices, adds data)
By Rodrigo Campos
NEW YORK, July 29 (Reuters) - U.S. stocks were set to rise slightly at the open on Tuesday following better-than-expected results from companies such as Pfizer and Merck and ahead of data on consumer sentiment.
* Merck reported better-than-expected quarterly results as new drugs offset declining sales of ones facing generic competition. Pfizer's higher-than-expected second-quarter earnings were helped by growing sales of its cancer medicines. Merck was up 1 percent in premarket, while Pfizer gained 0.6 percent.
* Shares of UPS fell 3 percent premarket after the world's biggest courier company slashed its earnings forecast for the year as it spent to boost capacity.
* Single-family home prices fell 0.3 percent in May on a seasonally adjusted basis, falling short of expectations calling for a 0.2 percent gain. The Conference Board's consumer sentiment for July is due at 10:00 a.m. EDT (1400 GMT). Continuación...