Slack Technologies Inc. shares are set to open Thursday on the New York Stock Exchange at $39.49 - down 2.97% from their Wednesday close after reports it was in merger talks with cloud-based software company Inc.

Sources familiar with the matter said a deal could be announced as soon as next week.

Following a report published by The Wall Street Journal Slack's share price rose 37.59% Wednesday to close the day at $40.70. Salesforce's share price is expected to rise Thursday morning by about half a percent to $248.00. On Wednesday the issue dropped 5.37% to $246.82 on the news.

Microsoft, which competes with Salesforce through its Teams app, saw its shares down. Microsoft's shares ended Wednesday lower from an opening of $215.01 a share to a close of $213.87 each.

There are few details about Salesforce's plan to acquire Slack. However, industry experts said the deal might be worth as much as $20 billion based on Slack's current market valuation.

Salesforce has been on an acquisition spree - taking over several companies under the leadership of its chief executive officer Marc Benioff. In 2018, the company acquired MuleSoft for $6.5 billion - its largest acquisition at that time. In 2019, the company paid a record $15.3 billion to acquire data visualization company Tableau.

If Salesforce moves ahead it could be the biggest acquisition in the software industry. It might rival Facebook's $19 billion acquisition of WhatsApp in 2014.

"This would be a game changer move for Benioff and co. to further build out its collaboration engine and product footprint as cloud spending ramps across the enterprise," analysts at Wedbush Securities said.

Sources with knowledge of the matter said a deal is not guaranteed and the parties are negotiating terms.

A merger might give the combined entity an edge over Microsoft and its Teams application. Slack previously said Microsoft was its "primary competitor" and a partnership with Salesforce might give it the boost needed to become more competitive.