A few days after Mexican billionaire Carlos Slim reported an 18% stake in the company, Saks (NYSE: SKS) adopted a poison pill, disclosed in a filing with the SEC.

Under the terms of the "shareholder rights plan," if Carlos Slim or anyone else acquires a stake of 20% in the company, other shareholders will be able to acquire shares at half price. The company said that the plan will "impose a significant penalty upon any person or group which acquires beneficial ownership of 20% or more of the Company's outstanding common stock without the prior approval of the Board of Directors."

Shareholders should be appalled. Shares of Saks closed at $4 on Wednesday, down from a 52-week high of $22.19. In 1993, the stock traded north of $15 per share.

So shareholders should not be happy with any plan that gives the company's current management and directors more control over the future: Their track record is one of miserable failure. Given Mr. Slim's track record of creating enormous wealth, shareholders would likely be better off with whatever plan he has up his sleeve.

The Wall Street Journal reports (subscription required) that "Saks spokeswoman Julia Bentley declined to comment on the timing of the announcement, but said that Saks had a rights plan for more than a decade that expired in March 2008."

It must be illustrative to look at the returns that shareholders have received over that period.