“The stock market is way up again today and we’re setting a record, literally all the time,” President Donald Trump tweeted on Jan. 16. He went on to add that if Hillary Clinton had won the 2016 election, “the market would have gone down 50% from where it was.” Love President Trump or hate him, there’s no getting around the fact that the stock market has done well since he took office on Jan. 20, 2017. And he makes sure to remind us. But how much credit for the stock market rally and growth belongs to the president?

As measured by the S&P 500, the stock market sits at 2,812 as of Wednesday. On Jan. 21, 2017, the day after Trump took office, the index was at 2,367. Not considering dividends, that’s an 18.8-percent return during approximately 18 months. Not bad.

What’s Causing the Stock Market to Rally?

Ken Rogoff, Harvard economics and public policy professor, discussed the stock market rally and several reasons for recent stock market growth on CNN recently. Interest rates are low, and have been for quite some time, despite several increases this year. When interest rates are low, companies borrow more, grow and expand, leading to greater profitability and rising stock prices. When fixed investment returns are low, investors — seeking decent returns — have nowhere to go but the stock market.

Improving global growth is another cause for the current rising stock market. As international economies improve, so do global companies’ stock prices. The World Bank forecasted global economic growth above 3 percent in 2018, following a stronger than expected 2017. Global businesses are improving manufacturing and trade as commodity prices are stabilizing. And that boosts stock prices.

Rogoff describes the economy as a big ship, difficult to turn around. When Trump came into office 18 months ago, the economy was growing, and the stock market was in the midst of an eight-year bull run. The president came into office with a nice tail wind behind the economy and markets.

For What Can Trump Take Credit?

Since becoming president, Trump has slashed corporate regulations — and companies love that. Fewer regulations translate into lower compliance costs and greater freedom to do business as they see fit. With lower costs and greater profitability, stock prices tend to increase.

The tax cut is also a big win for the president. Although the little guys and gals benefit, the greatest recipients of the tax plan goodies go to corporations. Lower taxes for businesses’ mean greater profits. Ultimately, more profitable companies command higher stock prices. That’s a Trump win.

Has Trump Had Best Stock Market of Any President?

Well, no. Comparing the S&P 500 returns during the first year of the first term of every president, Trump comes out fourth, according to research from CFRA by Sam Stovall. Roosevelt saw a 30.5 percent return in his first year, while Kennedy enjoyed a 27-percent rise. Third place in the first-year presidential stock market performance race goes to Bush Sr. with a 22.2-percent increase. Trump comes in next with an excellent 21-percent return in his first year.

Ultimately, Trump can take some credit for rising stock prices, just not all the credit. The economy is a big ship, as Rogoff says. There are many moving pieces that go into the economy and stock prices including interest rates, U.S. and international growth, public policy, taxes and more. No one person could possibly control the entire economic and stock market ship.

Barbara A. Friedberg, MBA, MS is a veteran portfolio manager, expert investor, and former university finance instructor. She is editor/author of “Personal Finance; An Encyclopedia of Modern Money Management” and two additional money books. She is CEO of Robo-Advisor Pros.com, a robo-advisor review and information website. Additionally, Friedberg is publisher of the well-regarded investment website Barbara Friedberg Personal Finance.com. Follow her on Twitter @barbfriedberg and @roboadvisorpros. As of this writing, she does not hold a position in any of the aforementioned securities.