The largest investors in Corrections Corp. of America and AmSurg this spring sold tens of millions of dollars worth of their stock, cutting their stakes to half of what they were at the end of 2011.

At Lazard in New York, fund managers lowered their holdings in CCA — which has climbed more than 40 percent year to date — to 4.3 percent from 8.8 percent in the second quarter. As of Dec. 31, they owned more than 10 percent of the prison management company. The firm remains the No. 1 CCA investor, barely edging out a pair of hedge funds pushing the company to convert to a real estate investment trust.

The AmSurg moves by Fidelity Investments managers were almost as extreme: They trimmed their holdings in the surgery center chain to 7.4 percent as of June 30, down from 11.2 percent in March and 14.3 percent at the end of last year. The sales may have taken Fidelity parent FMR down to No. 2; fund giant Wellington Management, which owned 8.3 percent of  AmSurg in late March, has not yet filed its Q2 holdings report.

AmSurg shares also have done well this year, climbing about 20 percent and notching all-time highs.