It’s rare the executive branch weighs in on equity valuations. But sometimes a president just can’t resist.

Take Tuesday, when Donald Trump said American shares are giving investors “a tremendous opportunity to buy.” Reasonable people can differ on whether it mattered, it’s hardly the first time he’s mentioned stocks, and Trump gets a fair amount of blame lobbed at him for the sell-off as well. Whatever the case: he said it, and the S&P 500 shot up 5 percent after four straight days of losses and the worst Christmas Eve trading session ever.

Perhaps the most famous instance of presidential stock prognostication was in March 2009, six days before the financial crisis bottom, when Barack Obama told reporters that “profit-and-earnings ratios are starting to get to the point where buying stocks is a potentially good deal.” His comments came a day after the Dow dropped below 7,000 for the first time since 1997 and the S&P 500 hit its lowest level since October 1996. Even with the recent rout, the S&P 500 is up more than 250 percent since March 2009.