1. The hangover: It was fun while it lasted but investors are now dealing with a post-rally hangover.
It's a sharp change in mood for U.S. stocks, which rallied to hit record highs earlier this week after President Trump delivered a well-received address to Congress.
2. Fed focus: When the head of the U.S. Federal Reserve speaks, investors listen.
Fed chair Janet Yellen is set to give a speech at 1:00 p.m. ET in Chicago, Illinois, to discuss her outlook for the U.S. economy.
Fed vice chairman Stanley Fischer is also giving a speech on Friday about monetary policy in New York. It's due to start at 12:30 p.m.
3. Stocks to watch -- Costco, WPP, Nintendo: Shares in Costco ( dropped in extended trading after the retailer issued a disappointing earnings report. )
WPP ( stock was lower by about 6% in London after the advertising conglomerate reported earnings. )
Investors balked at the "nasty combo" of disappointing forecasts for 2017 and a slowdown in the final quarter of 2016, according to Mike van Dulken of Accendo Markets.
But let's switch to something a bit more upbeat: Nintendo Switch!
Shares in Nintendo ( jumped by 3.7% in Tokyo after the company released its newest console, which is retailing for $300 in the U.S. )
4. Coming this week:
Friday - Fed chair Yellen speaks at 1 p.m., Nintendo Switch releases worldwide