Bank of America’s stock closed under $5 yesterday, the lowest point since early 2009. Why is that five-dollar mark important, besides being a convenient round number? (Well, honorary round number?)

As the Wall Street Journal explained it, “The importance of the $5 mark is that some money managers have to sell stocks priced below $5.”

The price rose this morning — it’s at $5.09 as I write this — but it’s not good news. Again, the Journal: “In any event, it’s terrible optics, as this bank, once the biggest in America, now fits some definitions of a ‘penny stock’.”