The indirect tax software and services company sold 21,500,000 shares with no shareholders offering stock. Underwriters have a 30-day option to purchase another 2,630,165 shares of Class A from the company and 542,335 shares from selling shareholder.  Vertex earlier estimated net proceeds of $290.3 million at $15-per share and $327.2 million if the underwriters exercise their option, so add about 27 percent to that at the $19 per share price. Goldman Sachs & Co. and Morgan Stanley were joint lead book-running managers