Billionaire brothers Samuel and Charles Wyly asked a federal judge yesterday to dismiss a Securities and Exchange Commission lawsuit accusing them of orchestrating a $550 million securities fraud.

In a filing in Manhattan federal court, the Wylys argued that the SEC failed to show they intended to defraud the government or directed others, including lawyers, to make misleading securities filings.

The Dallas-based siblings also urged the rejection of an insider-trading charge tied to their $4 billion sale in 2000 of Sterling Software to the company now called CA Inc.

They said the charge was based on a swap transaction that pre-dated the decision to sell.

An SEC spokesman said the agency — whose response is due by Dec. 13 — stands by its allegations.