Retailers Staples, TJX Companies and Urban Outfitters all lost ground after posting disappointing quarterly results.
Caterpillar slid on news its global retail machinery sales for the three months through April fell 13 percent from a year ago.
J.C. Penney slumped after Wells Fargo downgraded the retailer to underperform from market perform, citing valuation.
Red Robin Gourmet Burgers surged after reporting better-than-expected first-quarter results as restaurant comp sales rose more than 5 percent.
Smith & Wesson moved higher as Wedbush upgraded the gun maker to outperform and raised its price target to $20 from $13.
AstraZeneca rebounded from Monday's losses after a shareholder voiced disapproval over its rejection of Pfizer's latest takeover offer and urged it to resume talks. Fidelity, the company's 18th biggest shareholder, disagreed, saying Pfizer was not a suitable partner.
Aeroflex zoomed higher after British aerospace and defense supplier Cobham said it would buy the U.S. communications equipment maker in a deal valued at $1.46 billion.
Dish Network lost ground after Verizon Communications CEO Lowell McAdam shot down rumors that the company was in merger talks with the satellite TV operator.
Target declined on news it was replacing the head of its troubled Canadian operations.
Clovis Oncology climbed after the drug developer said the FDA had granted breakthrough therapy status to its experimental lung cancer drug.
Carnival rose after Morgan Stanley raised its rating of the stock to equal weight from underweight, citing the company's cost controls.
Vodafone fell after the company said its 2015 earnings would be adversely affected by investment in its network to increase speed and coverage.
Allergan gained ground. Canada's Valeant Pharmaceuticals said its upcoming sweetened offer would not be an all-cash bid. Valeant, which launched a $47 billion unsolicited bid on April 22, plans to announce its improved bid on May 28.
Medtronic and Edwards Lifesciences both moved lower. The two settled their heart valve patent fight as Medtronic agreed to pay royalties so it can continue to sell the devices.
(Read More: See CNBC's Market Insider Blog)
—By CNBC's Rich Fisherman.
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