The U.S. Securities and Exchange Commission (SEC) is investigating firms listed on the New York Stock Exchange (NYSE), with a particular focus on their first day of trading. (The Wall Street Journal)

Talking point: The SEC is looking for messages sent just prior to firms’ IPOs. It’s sent letters to companies, including electronic-trading firm Citadel Securities, requesting those messages, as well as their policies for abiding by NYSE rules. The SEC is reportedly particularly interested in companies that achieved high valuations while private prior to listing publicly, though it is not clear what kind of potential misconduct it is investigating. This adds to at least five separate investigations large tech firms are facing in the U.S. For Slack, this comes as the company is facing growing competition from Microsoft and has had its shares drop more than 40 per cent since it went public. Earlier this month, the company reported revenue of about US$169 million, above analyst expectations.