​U.S. companies conducted $528 billion in mergers and acquisitions (M&As) last year, a 13 percent jump from 2002, according to FactSet Mergerstat LLC, a global mergers and acquisitions research firm in Santa Monica, Calif. That growth marked the first year-over-year upturn since 2000.

Among the top megadeals were:

• Bank of America’s $47.8 billion agreement to buy FleetBoston Financial Corp.

• The St. Paul Cos. Inc. acquisition of Travelers Property Casualty Corp. for $16 billion.

• Anthem Inc.’s $14.8 billion purchase of Wellpoint Health Networks Inc.

• Manulife Financial Corp.’s deal to buy John Hancock Financial Services Inc. for $10.7 billion.

But it wasn’t just the titans that spurred M&A escalation. Deals worth $50 million to $90 million chalked up a 12 percent hike in 2003 over 2002, according to FactSet Mergerstat data.

The boom is likely to continue this year. A survey conducted in December 2003 by Thomson Financial in New York and the Association for Corporate Growth in Glenview, Ill., found that 85 percent of 1,301 business executives from companies of all sizes—those with annual revenues of less than $5 million to those with revenues of $500 million or more—think the M&A environment will improve this year, and 90 percent of those polled expect the number of deals to rise.