The S&P 500 is no doubt soaring: It reached an all-time high of 2,591 at close Monday – up 21% since Trump was elected on Nov. 8, 2016. U.S. companies on the index have gained $3.8 trillion in value in the past year. Taken together, they are now worth $23 trillion.

But despite Trump’s penchant for comparing himself favorably to past presidents – he claimed he accomplished more in his first year than any president except Franklin D. Roosevelt and told supporters he could be “more presidential than any president” except Abraham Lincoln – Trump isn’t at the top of the pile when it comes to the biggest first-year market gains.

One only has to look as far back as George H.W. Bush’s first year to find better gains. Trump comes in fourth behind Franklin D. Roosevelt, John F. Kennedy, and Bush.

On Air Force One en route to Asia on Monday, Trump told reporters, “The reason our stock market is so successful is because of me. I’ve always been great with money, I’ve always been great with jobs, that’s what I do. And I’ve done it well, I’ve done it really well, much better than people understand and they understand I’ve done well.”

The 21% gain in the S&P in the year since Trump was elected compares favorably to the average of 6.1% for the first year for other first-term presidents. Moreover, the stock market’s gains under Trump have been surprisingly steady. Eisenhower and George W. Bush presided over the strongest rally in the one month following their respective elections. But a year later, those gains were either nearly or entirely obliterated.

But Trump’s assertion that he is responsible for that steady gain in the market is considerably more problematic, says Howard Silverblatt, a Senior Industry Analyst at S&P Dow Jones Indicies.

U.S. companies have done quite well for themselves, Silverblatt says, with sales expected to grow 5.9% year-over-year in the third quarter, based on companies that have already posted earnings. And that’s all without big stock buybacks, says Silverblatt. Buybacks tend to make earnings per share look rosier.

“Sales have set a quarterly record,” he said. “It is something to get excited about.”

The U.S. has gained more than 5.2 trillion dollars in Stock Market Value since Election Day! Also, record business enthusiasm.

— Donald J. Trump (@realDonaldTrump) October 16, 2017

Companies have also benefited from strong economic tailwinds. Interest rates have maintained historic lows, making it cheaper to borrow money. International markets have also been strong, as the oil glut begins to taper and Chinese and European economies strengthen — helping U.S. multinationals surge amid potential increases in international sales.

Trump can definitely claim some credit for the surging market thanks to his promise of tax reforms, Silverblatt says. Investors are now eagerly watching Washington as Congress moves on the new Tax Cuts and Jobs Act. The GOP-proposed plan would slash the corporate tax rate from 35% to 20%. Wall Street analyst are expecting those cuts to boost corporate bottom lines.

“Earnings supported us,” said Silverblatt of the rally. “But income taxes are going to be really important once earnings start to die down.”

And it may be too early for Trump to tie the stock market gains to own presidency. Treasury Secretary Steve Mnuchin, one of the architects of the tax reform bill, warned in October that stock markets may see a significant reversal should the tax bill fail to pass.

George H.W. Bush’s stock market shed part of its gains by the time he left office, while Herbert Hoover’s stock market gains began to slide in October 1929 at the start of the Great Depression.