The Washington Post has this article describing some of the cross-examination of former WorldCom CFO Scott Sullivan in the Bernie Ebbers criminal trial.  One key issue: what prompted Sullivan to begin making improper accounting entries to permit WorldCom to meet it's expected financial results?  The article reports that according to Sullivan's testimony, the fraud was the result of Ebbers telling him repeatedly to "hit the numbers," which he took as an order to make accounting adjustments :

As the afternoon wore on, Sullivan began to look tired and blink far more frequently, and Weingarten pressed harder.

Sullivan has testified that he told Ebbers in each of seven quarters about "adjustments" he made to the company's books to bring the revenue and earnings in line with Wall Street's expectations. He also said Ebbers responded each time by saying the company had to "hit the numbers."

"You took his words [hit the numbers] as a command to go out and commit accounting fraud?" Weingarten asked.

"Yes, I took that as an order to make adjustments and hit the earnings per share number, yes. He said we had to hit the numbers," Sullivan responded.

"You were a member of the board. You had been named CFO of the year. You had cashed in some $30 million in [stock] options, and you felt you had no choice but to interpret Mr. Ebbers's words 'we have to hit the numbers' as a command to go out and commit accounting fraud?" Weingarten asked.

"Yes, that is my testimony," Sullivan said.