American Capital 2nd-qtr profit beats estimates

* Q2 oper EPS $0.58 vs est $0.20

* Oper EPS boosted by $132 mln tax benefit

* Net asset value of $16.62/shr on June 30

July 31 (Reuters) - Asset manager American Capital Ltd posted second-quarter earnings above analysts' expectations, helped by a tax benefit.

Net earnings for the quarter was $237 million, or 71 cents per share, down from $410 million, or $1.13 per share, last year.

ACAS net operating income was $194 million, or 58 cents per share, boosted by a $132 million tax benefit related to a change in tax treatment of preferred stock dividends.

Analysts on average were expecting a profit of 20 cents per share, according to Thomson Reuters I/B/E/S.

ACAS, which counts billionaire investor John Paulson among its top shareholders, reported net asset value of $16.62 per share as of June 30, higher than the $15.71 per share recorded a year earlier.

Shares of the Bethesda, Maryland-based company closed at $9.96 on Tuesday on the Nasdaq. They were up about 2 percent in after-market trade.