A handful of IBD 50 stocks broke out of bases in heavy volume last week following mostly positive earnings reports. For the week, the list of leading stocks rose 1.9%, better than the S&P 500’s 1.1% gain. AmTrust Financial Services (AFSI) showed the strongest action. The New York-based provider of property and casualty insurance soared above a 39.74 cup-with-handle buy point Thursday after better-than-expected quarterly results.