Trump ranks No. 248 on the billionaires list this year with a net worth of $3.1 billion, according to Forbes, which released the rankings Tuesday.
Trump ranked No. 156 in 2016.
Forbes, which has tracked Trump since the list's debut in 1982, said the president's faltering net worth is due to weakening in the New York City real estate market.
Trump did not campaign with the magazine in an effort to boost his ranking as he's done in years past, said Luisa Kroll, Forbes magazine senior wealth editor.
"We'll see if he tweets today," Kroll told CNBC's "Squawk Box." "I know he cares a lot."
The president shares his spot on the list with the 27-year-old Spiegel, co-founder and CEO of the parent of Snapchat.
Spiegel was the youngest on the list, Kroll said. "And he's been the youngest for a number of years," she said. Spiegel took his ephemeral photo messaging company public on the New York Stock Exchange earlier this year.
Forbes used closing stock prices from Sept. 22, 2017, to compile the Forbes 400 list.
Microsoft founder Bill Gates tops the list for the 24th-consecutive year, with a net worth of $89 billion this year.
Amazon CEO Jeff Bezos was No. 2 spot for the second year in a row, with a net worth of $81.5 billion.
Berkshire Hathaway's Warren Buffett, who prior to 2016 held the No. 2 spot for 15-consecutive years, was third in 2017 with a net worth of $78 billion.
Forbes says the minimum net worth required to be counted among the richest hit a record high of $2 billion, up from $1.7 billion in 2015 and 2016.
The combined total net worth of all the 400 billionaires on the Forbes list was a record-breaking $2.7 trillion this year. That's up from $2.4 trillion in 2016.
— Disclosure: CNBC parent NBCUniversal is an investor in Snap.