People walk by the New York Stock Exchange on November 16, 2017 in New York City. Spencer Platt/Getty Images

President Trump in December 2017 publicly boasted about Wall Street gains, attaching the success to his campaign slogan: "Make America Great Again."

But those were the days of record highs. These days are less bullish.

Trump has not referenced Wall Street on his Twitter account in quite some time and for good reason: the stock market is in the midst of a slump, with worries of a global economic slowdown. Stocks on Friday closed lower, with the S&P 500 now 10 percent below its most recent all-time high in September.

Linking the stock market to White House economic policy may prompt the question: How has the stock market performed under the president? A look at the numbers reveals modest gains.

On Jan. 20, 2017, the day Trump took office, the S&P 500 closed at 2,271.31. The index most recently closed at 2,632.56, a gain of 14.73 percent.

The Dow Jones Industrial Average saw a slightly stronger gain, closing at 19,795.06 on Jan. 20, 2017, and closed this week at 24,285.95, a gain of 20.38 percent.

The Nasdaq has seen the sharpest gain. It closed at 5,555.33 on Jan. 20, 2017, and is now at 6,938.98, a gain of 22.14 percent.

But how the market performs during an administration is not really something a president should discuss. As economist Jason Furman noted in a February report in Politico, presidents "have a limited and very indirect effect on stock markets and even on the economy more broadly."

"Using day-to-day stock market movements as a proxy for expressing this confidence is ... a financial, economic and likely political mistake," Furman wrote.