UPS delivers a profit miss; Darden CEO steps down; Herbalife tumbles

Here is a look at some of the stocks the Yahoo Finance team will be watching for you today.

UPS (UPS) shares fell before the bell. The package delivery company reported earnings that missed analysts' estimates by $0.04 a share. However, revenue came in slightly better than expectations, up 5.6% compared to a year earlier. The company said profits took a hit due to a charge related to retirement liabilities of some union employees. UPS also cut its earnings outlook for the year as it plans to increase technology spending to prepare for its peak shipping season.

Aetna (AET) reported earnings and revenue that blew past estimates thanks to rise in enrollments, which rose 5% to 23 million people. The company also continued to benefit from its acquisition of Coventry Health Care and raised its earnings outlook for the year.

Pfizer (PFE) reported better-than-expected second quarter earnings. However, revenue fell 1.5% from a year ago as sales of some of its key drugs decreased amid competition from generic brands. Pfizer also lowered its revenue outlook for the year.

Herbalife (HLF) tumbled before the bell after the nutritional supplement company reported earnings and revenue that fell short of analysts' estimates. Earnings fell 16% due to higher expenses. However, revenue rose 7% from a year earlier. It was the first time since 2008 it reported a profit miss. The company also cut its sales outlook for the year, but raised its earnings forecast. Herbalife has been under attack by billionaire investor Bill Ackman, who alleges the company is a pyramid scheme. Ackman has bet $1 billion against the company by shorting the stock.

Darden Restaurants (DRE) shares were higher in the pre-market after the restaurant-chain announced its chairman and CEO Clarence Otis is stepping down. The company which Monday completed the sale of Red Lobster has been under pressure from activist investors, such as Starboard Value, to slash costs and split up the company. Darden is also separating the chairman and chief executive roles, which clears the way for activist shareholders to gain seats on the board. The changes are seen as the another victory for activist investors this week, following the sale of Family Dollar to Dollar Tree yesterday after Carl Icahn put pressure on the company to sell itself.

Twitter (TWTR) also on investor’s radar. The micro-blogging site is scheduled to release its second quarter earnings report this afternoon. In addition to user growth and ad revenue, many were looking for Twitter to release new metrics to show that Twitter reaches people in the general public who aren't signed up to use the site. However, Recode reported that Twitter will not release those new metrics today.