As part of their continuing quest to give away much of their worldly wealth, Microsoft Corp. Chairman Bill Gates and his wife, Melinda, have transferred another $5 billion to their foundation, it was announced yesterday.

All by itself, that sum would be enough to create the country's sixth-largest foundation. When added to the amount the couple has already given, it means the Gates Foundation is now the world's wealthiest, its $21.8 billion endowment narrowly edging out the $21.4 billion held by Britain's Wellcome Trust.

The news, which was confirmed in a brief statement from the foundation in response to press inquiries, is part of a recent spate of high-tech giving. Jim Clark, co-founder of the Internet browser company Netscape, gave $150 million to Stanford University. Michael Dell, founder of Dell Computer Corp., and his wife, Susan, donated more than $100 million worth of stock to start a foundation specializing in education and children's health.

Last week, James Barksdale, former chief executive of Netscape, and his wife, Sally, donated $100 million to the University of Mississippi Foundation for the creation of an institute to combat illiteracy.

And this may be only the beginning. "Compared to the amount of wealth being created in the high-tech field, there's still a great potential for a lot more giving," said Stacy Palmer, editor of the Chronicle of Philanthropy.

The 44-year-old Gates, who earlier this month stepped down after a quarter-century as chief executive of Microsoft, has been increasing his giving rather dramatically.

"In 1997, I thought I was going to run a library program with a $200 million commitment," said Gates Foundation President Patty Stonesifer. "During that time, Bill and Melinda realized there were many things they could be doing right now, even before they were ready to make a full-time commitment."

Last year, the foundation committed itself to disbursing $2 billion for minority scholarships and to the Global Fund for Children's Vaccines. It actually wrote checks for $800 million. U.S. law requires charitable foundations to give away at least 5 percent of their assets each year.

According to the Chronicle of Philanthropy, the second largest U.S. foundation is the Ford Foundation, with $13.1 billion, followed by the Packard Foundation at $13 billion, the Lilly Endowment at $11.2 billion and the Johnson Foundation at $8.3 billion.

The Gateses "are quick to say the majority of their philanthropy still lies in the future," Stonesifer said. "They've said they were going to give away the vast majority of their resources. Bill still is very focused on his leadership of Microsoft, and both of them are focused on their family."

Exactly how much the Gateses will have available to give away seems a matter of conjecture. One unauthorized Web site that specializes in the topic, the Bill Gates Personal Wealth Clock, said it was $114 billion yesterday. But the Bill Gates Net Worth Page, which is equally unofficial, pegged it at $80 billion. Neither the foundation nor Microsoft itself offers a number.

The high-tech world's apparent lag in charitable giving is due to a confluence of reasons. For one thing, many insist that more giving is done than is reported. It's just done anonymously or quietly.

For another, much of the wealth has come so fast to those who are so young that they have been much more focused on making it than spending it.

Both of those traits might be true of Michael Dell, who may be one of the richest men in the world but is still only 34. The existence of the Michael and Susan Dell Foundation became known only after it sold 2.7 million Dell shares this month.

A family spokeswoman told the Chronicle of Philanthropy that the couple started the foundation "because they want to extend the charitable giving they have done in the past," but declined to specify the amount of the foundation's endowment.

A final reason for the high-tech world's apparent stinginess is that nearly all its wealth is tied up in stock. It's new money, in all senses of the word.

"All that uncertainty is what keeps people from giving it away, because you don't know whether it's going to last for the next five minutes," said Palmer of the Chronicle of Philanthropy.

Barksdale, who was 57 yesterday and worth more than $700 million, is fond of saying that if he dies with a dollar left, it means he has miscalculated. "Accumulation of wealth has no purpose," he said. "Its purpose is to accomplish something. Obviously you do something for your children, but after a certain point it spoils people to give them money. So what do you do with the rest?"

He also said the fact that so many of his peers were starting to give had influenced him.

"Ted Turner made that statement that we ought to quit worrying who's on the Fortune 500 and start worrying who's on the list of givers," he said. "I made mine public so it could be an example for others."