The U.S. stock market is booming. Since Donald J. Trump declared that he had won the presidency for the second time, traders have been happily driving share prices up.

Stocks have reached new highs, the dollar is strengthening and bond yields have moved up in the expectation that Mr. Trump’s victory will mean not only accelerated economic growth, but, quite possibly, another surge of inflation.

Making cool financial calculations about the implications of the Trump triumph, as market traders are doing, may be the last thing on the minds of voters who had hoped that Vice President Kamala Harris would win the presidency and that Mr. Trump, a twice-impeached felon, would never become president again. If you are afraid that democracy is in imminent danger, how your investments are performing may seem the least of your worries.

Yet regardless of your political orientation, you need a financial plan that you can rely on even in times of stress, particularly for investing.

Will the markets rise or fall further, now that a second Trump administration is in our future? Tax cuts are likely, but Mr. Trump has also repeatedly vowed that he will impose tariffs on China and on many other countries as well, measures that could lead to increased inflation, reduced international trade and a drag on the global economy. And while Mr. Trump has promised to crack down on illegal immigration and to initiate mass deportations, the effects of such policies on the U.S. labor market, and on industries like construction and agriculture that depend on immigrants, can’t be reliably estimated.

It’s unlikely that the markets have fully absorbed the implications of all the policies Mr. Trump and his allies espoused over the course of an unruly political campaign. For one thing, political control of the House of Representatives is unsettled, so it’s not clear whether Mr. Trump can enact his most ambitious policies.