Billionaires Are Buying These 2 Ultra-High-Yield Dividend Stocks Hand Over Fist. Are They Smart Buys for Your Portfolio?

These high-yield dividend payers have what it takes to pump up your portfolio's passive income stream.Billionaire investors generally don't necessarily need dividend income to make ends meet. They buy dividend-paying stocks because they know that companies committed to returning a portion of earnings to shareholders tend to outperform ones that don't.In the first three months of the year, billionaire hedge fund managers bought millions of shares of Pfizer (PFE -1.78%) and AT&T (T -1.33%).Both of these divid ...