Yesterday was one of those great days in the market, wasn't it? A strong start and an even stronger finish. Big up days feel good. Today I feel like taking the day off for a round of golf. And why not? I deserve it for sticking with my plan and successfully carrying out my long term buy and hold investor's strategy.

Now, the fact is, any day is an OK day to go play golf. But days like yesterday are unlike most other days for the long term buy and hold investor. I believe that only the long term buy and hold portfolio strategy positions an investor to take advantage of days like yesterday.

Don't believe me? Well consider this scenario. Start with two hypothetical S&P500 portfolios in 1980. Portfolio A, the long term buy and hold portfolio, invests fully on day 1 and remains fully invested. Portfolio B, the uncannily unlucky market timer portfolio, also invests fully in the S&P500 on day 1. Our Portfolios B investor however, in an unbelievable series of unlikely events, sells all his shares at the close the day before the best performing 30 days in the S&P500 index. On seeing the error of his decision, he buys immediately at the close of each of these 30 best performing days.

What do you suppose is the difference today between the value of portfolio A and Portfolio B? The answer is nearly 75%. Missing the best 30 days' performance in the S&P500 since 1980 meant missing out on about 75% of the gains realized by a simple buy and hold strategy.

Maybe if I get some time later I'll check to see whether yesterday qualifies as one of the top 30. I'm certain if I shorten the time window enough it will be. It doesn't really matter though. A long term buy and hold investor gets to take advantage of not only the top 30 performing days, but also those that almost make the top 30.