Alphabet just sold 83% of its position in a leading cybersecurity stock.Each quarter, investment firms that manage over $100 million are required to file a form 13F with the Securities and Exchange Commission. Essentially, a 13F breaks down which stocks institutional money managers bought and sold during the last quarter -- thus providing some clues as to what the "smart money" on Wall Street is thinking.Outside of traditional investment funds, though, large corporations with investments in other companies ...