From the date burglars broke into the Democratic National Committee headquarters in the Watergate complex in 1972 until the resignation of President Richard Nixon two years later, the S&P 500 fell 25 percent.

That might seem to be evidence that impeachment battles and constitutional crises are bad for business and, consequently, for financial markets. Except in that same span, the West German stock market fell by 26 percent, despite the absence of any equivalent political crisis. And during a more recent impeachment, Bill Clinton’s in 1998, the S&P actually rose 22 percent.

In the 1970s, markets weren’t responding to troubles and high drama in Washington; they were adjusting to oil embargoes and a spike in inflation. In 1998, they reflected a booming economy. And those episodes have something to tell us today as an effort to impeach President Trump begins.

On Tuesday afternoon, some analysts attributed a drop in major stock indexes, as well as a rally in Treasury bonds, to the opening of the impeachment inquiry. But these historical episodes of impeachment drama show that any moves driven by political headlines tend to be modest and short-lived. Economic fundamentals matter a lot more.