UPDATE 2-Mexico's Cemex quarterly net profit falls 7 pct

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MONTERREY, Mexico, Oct 25 (Reuters) - Mexico's Cemex, the world's top building materials company by revenue, posted a 7 percent fall in third-quarter net profit to $780 million on Thursday, slightly above analysts' expectations.

The slide in profit was due to an extraordinary $100 million gain from an asset sale in the third quarter of 2006 and extra costs generated by Cemex's July 2007 purchase of Australia's Rinker.

Cemex (CX.N: Quote, Profile, Research, Stock Buzz)(CMXCPO.MX: Quote, Profile, Research, Stock Buzz) said its July-to-September revenues rose 31 percent to $6.1 billion. Earnings before interest, taxes, depreciation and amortization (EBITDA) rose 23 percent to $1.4 billion, the company said.

A Reuters survey of six analysts forecast, on average, that Cemex's quarterly net profit would be $750 million.

Cemex's sales in the United States, its top market, rose 57 percent in the quarter to $1.7 billion and EBITDA rose 25 percent to $420 million as the Monterrey-based company integrated Rinker into its results for the first time.

The results reflect Rinker's strong presence in the United States, which is experiencing a crisis in its subprime mortgage sector that caters to borrowers with poor credit histories. That is bad news for a sector also suffering from an inventory build-up and an increasing number of borrowers falling behind with mortgage payments.

As a result, Cemex's U.S. cement volume fell 1 percent in the quarter. "Building materials dynamics in the U.S. continued to be driven by the ongoing downturn in the residential sector," the company said in a statement.

Cemex, which operates in more than 50 countries, paid $15.3 billion for Rinker. Cemex said its net debt at the end of the third quarter was $19.2 billion, an increase of some $15.1 billion during the quarter, due to the Rinker acquisition.