Given the likelihood of a return of significant market volatility, periods of downward pressure will continue to be associated with price overshoots and undue contagion. For investors willing to stomach lots of mark-to-market risk, these gyrations will offer an opportunity to gain exposures at attractive prices to names possessing solid economic and financial fundamentals. And during the periods of upward retracement, these same investors will have the opportunity to accumulate cash, while continuing to upgrade the quality of their holdings.Anchored by the notion of “buy and hold,” many long-term investors will naturally resist adding a tactical component to their investment approach. But failing to do so could also cause them to risk losing sight of a larger reality that volatile markets are now signaling increasingly consistently.- from Market Calm May Be Short-Lived - Mohamed A. El-Erian
Buy and Hold is not really "Buy & Hold".
Here's a more local example.