Salesforce has held talks to acquire Slack, and a deal could be announced as soon as next week, according to a person familiar with the matter.

Shares of Slack rose as much as 32 percent Wednesday after the Wall Street Journal first reported that Salesforce held talks to buy the company. Salesforce stock dropped around four percent on the news. The company is also scheduled to release its third-quarter earnings on Dec. 1.

Salesforce has been on an acquisition spree, taking advantage of its market cap growth in recent years to buy growing companies. It acquired MuleSoft for $6.5 BN in 2018, the company’s biggest deal ever at the time, to help connect cloud applications. The following year it spent more than twice that amount on Tableau, acquiring the data visualization company for $15.3 BN.

Slack would be one of the biggest software deals ever for the industry. It would rank among IBM’s $34 BN purchase of Red Hat in 2019, Microsoft’s $27 BN purchase of LinkedIn in 2016, and Facebook’s $19 BN purchase of WhatsApp in 2014.

After the news broke out, shares of Microsoft, which competes with Slack through its Teams offering, also dipped slightly.

In 2016 TechCrunch reported that Microsoft looked at buying Slack for up to $8 BN, but no deal came about. Later that year Microsoft introduced the Teams communication app.

According to the Wall Street Journal, i a deal is not guaranteed and the talks could fall through.