It’s only natural.

After a long year of gloomy news and falling markets, companies are getting out and shopping.

The days of multibillion-dollar Mondays appear to be back, with new mergers announced just about every week this month. Today’s big deals added up to $13 billion worth of activity, as drug company Abbott Laboratories announced its purchase of Belgian firm Solvay SA’s drug business, and Xerox announced its purchase of Affiliated Computer Services Inc.

“History just repeats itself over and over and over,” said Bob Profusek, an attorney with Wall Street law firm Jones Day. After a major market correction, as we’ve seen in the last year, “They’re followed eventually by very substantial upticks in M&A activity. It’s really a function of the capital markets.”

With stocks moving higher, acquisition targets don’t feel they’re selling out at fire-sale prices, and buyers are eager to strike before the prices rise even higher.

Profusek said after an eerily quiet July, the increased activity of the past month has been of a certain sort—either companies with large balance sheets able to fund their own purchases or private equity firms picking up distressed assets.

“I wouldn’t say it’s rocking and rolling yet, but it’s getting close,” Profusek said. “We’re enthusiastic. But until the banks get more willing to lend, it’s going to be dominated by the giant deals or distressed.”

The value of U.S. deals announced so far in September is $48.6 billion, compared to $28.14 billion in August, according to Dealogic.

Where you’re not seeing as much activity, yet, is in the midsize deal that would need financing from banks—the $300 million to $1 billion deal with heavy bank backing.

The big mergers have ranged across sectors. But they have something in common. Most have been meant to strengthen companies in some key strategic areas, and at least some have ranked among the biggest deals ever done by the companies in question.

“It’s a strategic market,” Profusek said.