According to the New York Times, Slack, the four-year-old workplace messaging company, said on Tuesday that it had raised $427 million in new funding, just a year after its last huge infusion of money. The latest round values the company at $7.1 billion.

Slack's appetite for funding and its eye-popping leaps in valuation are becoming normal in the private investment market, where giant funds are eager to write oversize checks to start-ups with momentum and scale. In the first seven months of the year, 268 companies raised "mega-rounds" of $100 million or more, a record pace.

Based in San Francisco and Vancouver, British Columbia, Slack says it has eight million daily users, double its total from around a year ago. Many of its users do not pay for access to the service. More than 70,000 groups pay, the company said.

Slack's growth has made it a darling among investors and potential acquirers. In 2015, when Slack was worth $2.8 billion, Stewart Butterfield, the company's chief executive and a co-founder, said it was "the best time to raise money ever." Last year, Slack raised $250 million in capital from SoftBank Group's Vision Fund, among other investors. That funding valued Slack at $5.1 billion.

The company has fielded takeover interest from Microsoft, Amazon and Google. When Microsoft introduced its own Slack competitor, called Microsoft Teams, in 2016, Slack took out a full-page newspaper ad offering advice. "We're genuinely excited to have some competition," read the ad, signed "Your friends at Slack."

Dragoneer Investment Group and General Atlantic led the round. They were joined by T. Rowe Price Associates, Wellington Management, Baillie Gifford and Sands Capital.