Retail investors have a great opportunity to join the smart money right now.Investors looking for stock ideas may be wise to follow what some of the wealthiest money managers in the world are doing. Luckily, it's easy to see what many of them have been up to recently thanks to required filings from the Securities and Exchange Commission (SEC).It's rare for a lot of billionaires to all agree on a single investment. After all, the only way a market works is if there are both buyers and sellers. But every so o ...