That’s something Donald Trump voters probably didn’t think they’d say a month ago. But stock market investors who are enjoying the post-election rally—dubbed the “Trump Bump—owe a major debt to the controversial bank that became a political lightning rod in the presidential campaigns.

The Dow Jones Industrial Average closed Friday at a record high of 19,756.85—the index’s 14th record close since Trump won the election exactly a month ago. The Dow has risen 7.8% in that time, putting it in spitting distance of reaching 20,000, just weeks after breaking through 19,000 for the first time.

While the S&P 500 has gotten a Trump boost, too, it has lagged behind the Dow. Up 5.6% over the same period, the S&P 500 also set a new record high on Friday, but only for the seventh time since the election, according to S&P Global—half as many times as the Dow.

There’s just one big reason for the Dow’s outperformance, and it’s probably not what you thought. Sure, the Dow only has 30 stocks in it, of which only five have fallen since the election. Visa (V) has performed the worst, down 4.5%, with Johnson & Johnson (JNJ) a close second. And yes, the Dow has a heavy component of large industrial and energy companies which have recently soared on expectations that President Trump and his administration will sponsor new infrastructure spending projects and oil pipeline expansion.

Indeed, the Dow’s faster rise compared to the S&P 500 plays into some investors’ belief that Trump’s economic policies will help the sectors that have traditionally employed U.S. middle-class workers, namely industrial and manufacturing companies.

But those companies have had a relatively small part in the Dow’s dramatic rise towards 20,000. In fact, the company that has played a staring role in the Dow’s outperformance does not actually employ a lot of traditional middle-class Americans: Goldman Sachs (GS).

Goldman Sachs stock is responsible for a whopping 29% of the Dow’s overall bump since the election. Put another way, Goldman Sachs alone is responsible for more than 400 points out of the Dow’s total 1,400-point gain during the “Trump Bump.” Also on Friday, Trump himself offered a White House job to a top Goldman Sachs executive, Gary Cohn, following appointments of two other former Goldman employees to the new administration.

The second biggest contributor in the Dow’s record-breaking journey is also a bank, but it doesn’t even come close to Goldman Sachs’ influence on the market index. J.P. Morgan (JPM) has risen more than 22% since the election, second only to Goldman stock’s 33% gain—but it can only take credit for about 7% of the Dow’s increase. (This is due to the fact that the Dow index is price-weighted, and because Goldman Sachs is now its most expensive stock at $242 per share, that bank holds bigger sway on the index average.)

Indeed, if you took Goldman Sachs out of the Dow, the index would only be up 5.5%, less than the S&P 500.

Of course, the banks also had a lot to do with the rise of the S&P 500, which is weighted by market-cap, during the same period: Nearly 36% of the S&P 500’s returns since the election came from financial stocks, according to S&P Global. Bank stocks have benefited from both the anticipation of higher interest rates, which the Federal Reserve is expected to raise next week, as well as the belief that the Trump administration will roll back some of the more onerous financial regulations stemming from the Dodd-Frank Act. Without the financial sector, the S&P 500 would only be up 3.6% in the past month.

While Goldman itself has been critical of the President-elect, it may want to thank Trump too.