Treasury Secretary Timothy Geithner urged banks to increase transparency in the over-the-counter derivatives market by making prices available on centralized computer platforms.

Increased regulation is needed to reduce risk to the financial system, Geithner said yesterday in a news conference in Washington. He laid out a framework in March for more policing of financial markets as the worst credit crisis since the Great Depression caused more than $1.4 trillion in writedowns by banks and financial companies worldwide.

The OTC derivatives markets must be moved “onto regulated exchanges and regulated transparent electronic trade execution systems,” Geithner said yesterday in a letter to Senator Harry Reid, the Democratic Majority Leader from Nevada.