Lay and former Enron Chief Executive Jeffrey Skilling contend that short-sellers had mounted a concerted attack on Enron stock that year that helped drive it into bankruptcy protection. Selling stock short is essentially betting the price will drop.

On the second day of Lay's cross-examination at his fraud trial, prosecutor John Hueston played a tape of Lay telling Enron employees in October 2001 that Enron was under attack ''just like America's under attack by terrorism.''

Lay said he was referring in that remark to short-sellers and other forces damaging Enron's stock price. During his opening statement, Lay lawyer Michael Ramsey had referred to the short-sellers as ''vultures.''

The defense contends there was no fraud by Lay and Skilling, but that short-sellers, along with a nervous stock market, negative media reports and theft by Enron's finance chief, sank the company.

Hueston displayed for jurors a brokerage statement showing Lay's son, Mark, shorted Enron stock four times in March 2001. Short-sellers borrow stock to sell on the market and buy back at a lower price, pocketing the profit.

''He wasn't a vulture, was he?'' Hueston asked. ''He wasn't trying to kill Enron in 2001, was he?''

''I would think not,'' Lay answered.

Hueston also sought to undercut Lay's contention that negative articles in The Wall Street Journal in late 2001 were partly to blame for the company's demise, suggesting concern about Enron was far from limited to the Journal.

The prosecutor showed jurors a note published by a Prudential analyst that criticized Enron's lack of transparency and said management had an ''obsession with semantics,'' the analyst said.

Hueston also went after Lay's decision not to disclose his sale of millions of dollars' worth of Enron shares back to the company from 1999 to 2001, in order to repay loans he had taken from the company.

Lay countered that annual filings with the Securities and Exchange Commission in 1999 and 2000 showed that he repaid the company loans - although those filings did not reflect how he repaid them. ''I always tried to comply with whatever the regulations and requirements were,'' he said.

The loans were on a line of credit extended to him by Enron. They are separate from loans Lay took from banks and that are the subject of bank-fraud charges that Lay will face in another trial while the Lay-Skilling jury is deliberating.

The questioning early Thursday, was less tense than on Wednesday, when Lay admitted he tried to contact potential witnesses during his fraud trial - including one who wound up testifying against him.

Lay acknowledged he tried to go through a friend to contact Vince Kaminski, a former top risk analyst at Enron, nine days before Kaminski testified for the prosecution. A federal prosecutor suggested Lay was trying to get his story straight.

''I was trying to reach Vince Kaminski a long time ago, before I even knew he would testify,'' Lay said Wednesday. ''I was trying to reconnect with Vince, to talk to him about some issues I wanted to talk to him about.''

Kaminski told jurors he got a cold reaction when he told Lay and other executives in October 2001 that Enron needed to ''come clean'' on questionable financial structures in the weeks before it crashed into bankruptcy proceedings.

Lay said he was not aware Kaminski was on the government's witness list.