It's been roughly three months since Apple replaced AT&T in the Dow Jones Industrial average, and during that time period, the stock and index have remained relatively flat. Meanwhile, AT&T shares have rallied more than 4.5 percent during that period.
"The 'curse of the Dow' is alive and well," strategist Nicholas Colas wrote Monday in a research note, referring to an old market watcher's belief that the stocks that join the Dow Jones Industrial Average tend to underperform the ones they are replacing.
Of course, the theory doesn't always mean bad news for the stock. Since 2009, the stocks that have been included in the Dow have posted an average 3-month return of 6.7 percent.