Warren Buffett triggered a Wall Street rally when he offered to bail out troubled bond insurers in the US. But when you look at the deal closer, it's actually better for Buffett and Berkshire Hathaway than it is for the market.

Let's look at the deal. Buffett is only offering to support the highest quality bonds in the insurers' portfolios. He doesn't want any of the the securitized debt, including junk sub prime debt that they began insuring from about 2005, which doubled their size in the process and got them in so much trouble.

Let's not forget, Buffett is a value investor. He buys in when he believes other investors are under-valuing. Late last year he targeted the bond insurers. With concerns about their long term viability building with the subprime crisis, he announced he was opening up his own bond insurance operation. I talked about that here.

What he is offering now is actually giving his new business a massive injection, a good kick start, by buying a big slice of the bond insurance portfolios the other insurers own. And buying just the good bits. As the Daily Reckoning newsletter points out, Buffett is not being altruistic.

"He's showing up at a house on fire and offered to save the most valuable goods, but only if he gets to keep them."

That's why the bond insurers have told him they are not interested. Colin Barr and Roddy Boyd at Fortune explain why.

And of course, Buffett himself acknowledges this. "When I go to St. Peter I will not present this as some act that should entitle me to get in. We're doing this to make money ... If you put up $5 billion, you ought to make some money," reports Reuters.

Yep, the Sage of Omaha isn't the world's most successful long term investor for no reason.