President Donald Trump unleashed a huge rally in stocks on Friday as he promised to “unleash every authority, tool, and resource” to combat the coronavirus pandemic.

The major stock indexes each recorded their best day since October 2008, when stocks rallied in response to the federal government’s plan to fight the financial crisis. The rally reversed much of the losses of the previous day, the worst single day for U.S. stocks since 1987.

The Dow Jones Industrial Average gained 1985 points to hit 23185, a rise of 9.36 percent. The S&P 500 ascended 9.29 percent. The Nasdaq Composite jumped 9.34 percent. The Russell 2000 index of smaller companies rose 7.6 percent.

The rally picked up steam as the White House event went on and several corporate leaders announced how their companies would contribute to the fight against the pandemic. Oil prices spiked higher as the president announced the U.S. would be purchasing oil for its strategic reserves.

Prior to the White House presentation, the major indexes were up by just 3 to 4 percent. They had sunk below their gains on the opening, largely fed by hopes of a potential deal between House Democrats and the White House, as investors grew worried that a deal might not happen and partisan politics could derail efforts to combat the economic effects of the coronavirus.

Nancy Pelosi, the House Speaker, made a short address prior to the White House event in which she outlined the Democrat proposals but made no mention of working with Republicans or the White House. She did not take questions from the press. This sparked concern that Democrat leaders had decided to pursue their own agenda rather than cooperation with the Trump administration. Major indexes sank following her address.

Even while the White House event was continuing, Senate Minority Leader Chuck Schumer was quoted by reporters as complaining, without evidence, that the president has “authoritarian” tendencies. The market seemed to shrug off this signal that Democrats remain mired in partisanship.