Informative article below about Bogle's position on a re-balancing strategy. The author doesn't find it an effective way to manage money (in his opinion of course) & claims that Bogle himself doesn't rebalance his own portfolio.

I am wondering out loud..... that if Wall Street itself thought that such an approach was the best use of their own trading account balances, why then have they have spent enormous sums of money on hardware and software in order to trade very large sums of money on a high frequency basis?

I also found it interesting that Bogle turned down the chance to have Vanguard offer up the first SPY etf - now the biggest fund in the universe. That very same SPY fund that Spy Pro employs within a trading strategy that has, historically, done far better than Bogle's rebalancing approach....and taken far less risk by being on the sidelines a reasonable amount of the time. 

With 2.5 trillion in assets, it seems that it is wholly in Vanguard's best interest to make it very difficult to trade within their normal stock fund offerings.

http://servowealth.com/resources/articles/john-bogle-misses-boat-rebalancing

http://www.minyanville.com/trading-and-investing/etfs/articles/Why-John-Bogle-is-Dead-Wrong/2/13/2013/id/48095