With raider Nelson Peltz taking a position in Kraft (NYSE: KFT), it was clear that he wanted more than his share of certificates. He began to push for improving shareholder value through things like higher dividends and stock buy-backs. Part of his argument was that Kraft had some units that performed poorly. Why, he asked, should the company keep them?

Why indeed? Kraft is close to a deal to sell Post cereals to Ralcorp for $2.8 billion.

According to The Wall Street Journal [subscription required], "Kraft and Ralcorp are discussing a stock-based transaction that would free both parties from tax liability. That would be done by first spinning off the Post business and then merging it with Ralcorp, leaving Kraft holders with equity in the merged entity." The deal may help Ralcorp compete with cereal giants like Kellogg (NYSE: K).

There is a problem with the plan. It has only been about a year since Kraft was spun out from Altria (NYSE: MO). Kraft's stock is down about 5% over the last year. The new management now has a chance to prove that it can improve operations rather than sell them.

A division sold is often an opportunity lost. Post is an old and well-established franchise. Shares of rival Kellogg are up 20% over the last two years, which means that the cereal business does not have to be a loser. Ralcorp clearly thinks it can improve the Post returns. So, why sell now?

Douglas A. McIntyre is an editor at 247wallst.com.