In Depth: The Alibaba IPO

'We're ready to go' for Alibaba IPO: NYSE chief

How NYSE clinched Alibaba deal
How NYSE clinched Alibaba deal

NYSE President Thomas Farley said Friday the exchange is confident ahead of the start of trading of Alibaba, but "not overconfident."

In an interview on CNBC's "Squawk Box," Farley said the exchange is prepared to deal with any issues that may occur. "In the case of Alibaba, with the sheer size and magnitude, we did some particular tests. We did three big tests including two industry tests on a weekend. We included our broker-dealers, customers. All of them went well. I think we're ready to go."

The biggest IPO ever is set to begin trading Friday morning on the New York Stock Exchange, which said all its systems were operating normally. The Chinese e-commerce IPO priced on Thursday night at $68 a share, the top end of the recently increased range. The offering is raising $21.8 billion.

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Mobbed by the press, Alibaba founder Jack Ma arrived at the exchange Friday morning, as market makers inside were preparing to open trading on the stock, which is expected between 10 a.m. and 11 a.m. ET. But Farley said he doesn't care when it opens. "It could be two hours. It could be three hours" after the market opens at 9:30 a.m. ET.

"We have a call open this morning. I expect 500 to 1,000 industry to be on that call. So we can react very quickly" if any problems arise, he said. "We're prepared no matter the circumstances."

CNBC tweeted the scene:

And so it begins! It's Alibaba IPO day at @nyse.

In a market status update issued to clients Friday morning, the exchange said, "Common Customer Gateways (CCGs) are open for members to submit orders. All NYSE systems are currently operating normally."

"We have humans and technology [on the floor] at that point of sale," Farley said. "Humans can say, 'Hey I want to slow this process down, if there's an imbalance of buyers and sellers or visa versa and make sure we get it right."

It seems he was taking a swipe at the technology-driven, electronic Nasdaq Stock Market, which presided over the botched IPO of Facebook in 2012.

—By CNBC's Matthew J. Belvedere. Reuters contributed to this report.