• The Dow Jones Industrial Average notched its ninth straight day of losses.
• A big Fed decision is coming Wednesday.
• Japanese automakers Nissan Motor and Honda Motor are considering a merger.

Here are five key things investors need to know to start the trading day:

1. (Dow)n in the dumps

The Dow Jones Industrial Average notched its ninth straight day of losses on Tuesday. It's the index's longest losing streak since 1978 and notably comes at a time when the broader market is faring just fine. Though the S&P 500 and the Nasdaq Composite both lost some ground on Tuesday, both averages are up for the month, while the Dow is down more than 3%. CNBC explains why the Dow is in such a historic funk and how concerned investors should be. And as always, follow live market updates.

2. Counting quarters

A big Fed decision is coming Wednesday, and Wall Street is betting on another quarter-point haircut. Futures market traders are pricing in expectations that the central bank will bring its benchmark borrowing rate down to a target range of 4.25% to 4.5%. Though the rate cut is widely expected, it's not nearly as welcome: A CNBC survey found that 93% of respondents anticipate a cut, but only 63% thought it would be the right thing to do.

3. Spending stopgap

Congress is days away from a government shutdown. Funding runs up to Friday, at the same time government leaders are set to adjourn for the holidays. Congressional leaders on Tuesday released the text of a bill that would fund the government through March 14. If passed, the stopgap bill would tee up another budget deadline just weeks into President-elect Donald Trump's new term. 

4. Merge ahead?

Japanese automakers Nissan Motor and Honda Motor are considering a merger. The companies are preparing to enter negotiations that could result in the competitors coming together under a holding company. The combined operation (including Nissan-backed Mitsubishi, in time) would amount to 8 million vehicles sales annually, according to Nikkei, which first reported the merger talks. That sales volume would put the tie-up on par with some of the world's largest automakers but still shy of annual sales by Toyota Motor and Volkswagen.

5. Suspect indicted

Luigi Mangione was indicted Tuesday on charges of murdering the CEO of UnitedHealthcare, Brian Thompson. The 26-year-old is charged with one count of first-degree murder in furtherance of terrorism and two counts of second-degree murder, one of which is charged as killing as an act of terrorism. He also faces charges related to possession of a weapon and of a forged license. Mangione faces a maximum possible sentence of life in prison without parole if he is convicted.

– CNBC's Brian Evans, Samantha Subin, Yun Li, Jeff Cox, Michael Wayland and Dan Mangan, and NBC News contributed to this report.