It was supposed to be the first technology initial public offering (IPO) of 2017.

Less than a day before AppDynamics Inc. was set to price its shares on January 25, a group of employees and investors boarded a plane to New York City to attend the traditional bell-ringing ceremony for new listings at the Nasdaq stock exchange, according to a person familiar with the details.

Technology executives, investors and financiers were closely watching the deal, considered a crucial bellwether among so-called unicorns headed for public markets.

The bell was never rung. Instead of updating investors on its projected market valuation, AppDynamics was the subject of a different announcement: It had agreed to be acquired by Cisco Systems Inc. for $3.7 billion.

The deal is seen by some advisers as the first in a long-expected wave of unicorn buyouts. With more than 150 companies valued at more than $1 billion and a temperamental IPO market, being acquired offers start-ups an exit from the funding rollercoaster and can also shield them from the regulatory and investor scrutiny that comes with a public listing. At the same time, it can create the risk that the start-up loses its culture, independence and key staffers when folded into a larger business.

While dual-track processes—when a company pursues both an IPO and gauges buyer interest—are common, people with knowledge of the industry say AppDynamics’ 11th-hour deal is the closest to listing day that they’ve seen a tech company get before selling instead.

A representative for Cisco declined to comment on the details of the deal, while representatives for AppDynamics didn’t immediately respond to a request for comment.

Bankers working on AppDynamics’ IPO were kept in the dark until moments before the official release, people familiar with the matter said, asking not to be identified as the details aren’t public. The roadshow for the IPO had been going well, and underwriters even thought the deal could end up oversubscribed, meaning investors wanted more shares.

They had already decided to increase the marketed price range to $12 to $14 per share from $10 to $12 apiece, which would give the company a market value of about $1.72 billion at the top of the range.

But behind the scenes, the company had tapped boutique advisory firm Qatalyst Partners to run a sale. AppDynamics deliberately chose an adviser with no links to its IPO underwriters to avoid any information about the potential deal leaking, the people said.

A representative for Qatalyst didn’t immediately respond to a request for comment.

Meetings with Cisco and its advisers took place late at night in hotel rooms during the IPO roadshow, and only after underwriters and investors had gone home, they said.

Cisco, based in San Jose, had been on the scene for months, initially holding discussions with AppDynamics about potential partnerships between the two companies, the people said. It’s a common move for software makers, which can team up and integrate certain services to jointly sell their products. Over the course of discussions, the people said, Cisco realized it wanted tighter integration: That meant making a knock-out offer.