 Productivity startup Monday.com, the self-styled operating system for work, made its debut as a public company on Thursday after a successful IPO that saw its stock pop up 15 in the first day of trading. Trading on Nasdaq under the ticker symbol MDNY, it was valued at 178.78 per share at the closing bell on Thursday, well above its listing price of 155, giving the company a market cap of about 7.8 billion a significant uptick from the 2.7 billion it was said to be valued at a year ago. 