The S&P 500 last month reached a new record high, officially confirming that we are in a bull market. This environment may feel new, but the index actually has been in bull territory ever since it started to rebound from bear market lows 16 months ago. Bull markets always are declared well after they've begun -- but this doesn't mean we've lost out on an opportunity to benefit from them. That's because these periods of expansion generally last for years, offering us plenty of time to invest in stocks that t ...