Slack Technologies Inc. is the latest beast to join the ranks of tech unicorns in the public market. And according to its updated S-1 filing with the U.S. Securities and Exchange Commission, the popular work-messaging app expects to pay Goodwin Procter $2.5 million in legal fees for its direct-listing IPO.

San Francisco-based Slack made its trading debut Thursday morning on the New York Stock Exchange. The stock, under the symbol WORK, opened at $38.50, nearly 50% above the reference price of $26 set Wednesday, valuing the company at $19.5 billion.