U.S. Stocks Fall a Third Week on Europe Concern

S&P 500 innovation companies slid the most among 10 groupsthis week, dropping 1.5 percent for the third straight week oflosses. Hewlett-Packard, the biggest personal-computer maker,fell the most among research shares afterwards it cut a billiondollars from its sales forecast for 2011 and missed analysts'profit projections. The shares slid 11 percent to $35.98.

Salesforce.com Inc., the largest supplier of customer-management software, advanced 8.7 percent to $146.61 for thebest weekly gain since November. The company, which sells cloud-computing applications that companies rent over the Web ratherthan install on their computers, forecast fiscal second-quartersales and profit that topped estimates as the company added5,400 clients in last quarter.