Lost amid the hype over Twitter’s initial public offering is another, possibly more enduring bit of good news: The markets are healthy.

“We’ve had $44 billion in I.P.O.s this year,” said Scott Cutler, head of global listings at NYSE Euronext. “This is actually the capital markets working extremely well.”

Since the start of the year, the Dow Jones industrial average is up 19 percent, the Standard & Poor’s 500-stock index is up 23 percent, and the Nasdaq composite index is up 28 percent.

“Companies of all sizes have access to capital in the public markets,” said Mr. Cutler, who joined the actor Patrick Stewart and a couple other eclectic Twitter users to ring the opening bell this morning.

Speaking after Twitter had begun trading, Mr. Cutler said he was pleased with the market’s initial reaction. “We were very comfortable with how things went today,” he said.

But he acknowledged that markets were fickle, and it was still early days for Twitter as a public company. “We’re never out of the woods,” he said.