Venture Capital

Messaging Startup Slack Seeks Up to $4 Billion Valuation in Funding Round

The company is said to be in talks to raise $150 million to $300 million in financing.

Stewart Butterfield, co-founder and chief executive officer of Slack.

Photographer: David Paul Morris/Bloomberg
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Slack Technologies Inc., which runs a messaging service for businesses, is seeking an investment that would value the company at $3.5 billion to $4 billion, according to people familiar with the matter.

Slack is looking to raise $150 million to $300 million as part of the round, said the people, who asked not to be identified because the terms aren't finalized. The talks are ongoing, and a lead investor has not been selected, the people said.