The "Black Monday" crash, when the Dow Jones industrial average plunged 508 points 30 years ago Thursday, was not that black for our president, at least according to an account he gave The Wall Street Journal a day later.

"I sold all my stock over the last month," the paper quoted Donald Trump as saying on Oct. 20, 1987.

True to form, the businessman then added to reporter Randall Smith, "The timing was no different than the Grand Hyatt — what do you think of it?" This was a reference to Trump's successful turnaround of the midtown hotel in the late 1970s as New York City was embroiled in a fiscal crisis.

The article did not offer any proof of Trump's sales.

This is not the only time Trump has claimed to be quite astute at timing the stock market. As a presidential candidate, his financial disclosure form filed with the Federal Election Commission in 2015 boasted of his stock market gains.

"Even though stock market purchases are not something that Mr. Trump has focused on in the past, and while only a small part of his net worth, 40 of the 45 stocks purchased went up in a relatively short period of time, creating a gain of $27,021,471, not including those stocks still remaining in the portfolio which currently have an unrealized gain of over $22 million," stated an accompanying press release with the form. In total, the schedule of stock transactions submitted showed Trump sold $94.4 million in stock in January 2014 for which he had paid $67.3 million.

CNBC's Michael Santoli (then with Yahoo Finance) pointed out at the time that it's impossible to tell whether that claimed 40 percent realized gain beat or underperformed the S&P 500 during this roaring bull market because no time frame was given for the purchases. Going by the makeup of the run-of-the-mill blue chips in Trump's portfolio, Santoli said it's more likely that he simply tracked pretty closely to the performance of the benchmark.