Oct. 4 (Bloomberg) -- U.S. online advertising spending topped $5 billion in the second quarter, a record for a three- month period, signaling that more advertisers are abandoning newspapers and television.

Companies boosted expenditures 25 percent to $5.1 billion from a year earlier, the Interactive Advertising Bureau and PricewaterhouseCoopers LLP said today in a statement. For the first half, spending rose to about $10 billion, also a record.

Google Inc. and newer entrants such as News Corp.'s MySpace and Facebook Inc. are benefiting as companies spend more to target Internet users. Spending on search ads, Google's main revenue source, accounted for 41 percent of all online ad spending in the first half, the study found. Display ads such as banners and video accounted for 32 percent.

Spending on network television spots fell 3.6 percent to $11.8 billion in the first half, while newspaper ads declined 5.8 percent to $12.9 billion, TNS Media Intelligence said last month. Radio ad spending fell 2.7 percent to $5.14 billion.

To contact the reporter on this story: Vivek Shankar in San Francisco at vshankar3@bloomberg.net

Last Updated: October 4, 2007 16:13 EDT