Update (1150ET): Slack shares are trading again, and they’re up a staggering 30% even though the deal isn’t anywhere near a sure thing.

Salesforce, meanwhile, is down 4%.

This could present an intriguing merger arbitrage opportunity for anybody who is still…trying to make money that way…since the end of the year is often a popular time for deals, and with stocks at record highs and rates still anchored, companies have the incentive to put some money to work.

Speaking on CNBC, Dan Ives said this deal “would make a lot of strategic sense [for Salesforce] as they look to penetrate on the personal collaboration front” creating what’s essentially a second major player rivaling only MSFT.

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Slack shares soared Wednesday, forcing a halt during an already abbreviated session, on news that software as a service pioneer and newly minted Dow 30 member Salesforce has held talks to buy the messaging/workflow company.

Any deal, according to CNBC, would likely value Slack at more than its current market capitalization of $17 billion and represent Salesforce’s largest acquisition ever. There is no guarantee the talks will lead to a deal, however.

Slack shares were halted after soaring 7% higher.

While shares of Salesforce slumped, dragging the Dow lower.

As Slack shares soared, the joke was on the Twitter bulls who had held out hope that Salesforce might buy Twitter instead. Salesforce CEO Mark Benioff took a close look at Twitter three years ago, but eventually revealed that shareholders were against such a deal. Interestingy, Benioff later revealed in his book that he slipped on a curb and sliced his leg open on his way to a meeting about securing financing for a Twitter buyout, which he took as a sign that he should listen to his advisors and abandon the deal.