Construction equipment company Caterpillar Inc on Friday said the U.S. Securities and Exchange Commission is investigating how it accounted for its July 2011 purchase of Bucyrus International Inc.

In its quarterly report, Caterpillar said the Sept. 10 subpoena from the SEC seeks information about its accounting for goodwill relating to the $7.6 billion takeover of Bucyrus, a maker of mining equipment.

Caterpillar said it is cooperating with the SEC and believes the matter will not materially affect its finances or liquidity.

In a separate statement, the Peoria, Illinois-based company also said it believes its accounting treatment for Bucyrus was "appropriate." Bucyrus had been based in South Milwaukee, Wisconsin.

Goodwill reflects intangible assets such as brand value and employee morale. It is often used as a measure of how much over book value, or the sum that a company's assets could fetch in a liquidation, a company pays to acquire a business.

Caterpillar said it had $6.8 billion of goodwill on its books as of Sept. 30, of which $3.76 billion concerned its resource industries operations, which include Bucyrus.

Shares of Caterpillar, a component of the Dow Jones industrial average, closed up $1.25, or 1.2 percent, at $101.41 in Friday trading on the New York Stock Exchange.