• The S&P 500 posted a record close to end the month and the quarter.
• East and Gulf Coast port workers are on strike.
• Nike reports quarterly results after the bell Tuesday, weeks after the sneaker giant announced it would replace its CEO John Donahoe.

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

1. In the green

The S&P 500 posted a record close Monday to end the month and the quarter. The broad market index rose 0.42% during the final trading session before October to close at 5,762.48. The Dow Jones Industrial Average also notched a record close, gaining just 0.04% to 42,330.15. The Nasdaq Composite advanced 0.38% to close out September. Follow live market updates as stocks enter the fourth quarter.

2. 'Meeting by meeting'

Jerome Powell's message this week: Don't get too used to half-point cuts. The Federal Reserve chair said Monday that the central bank will let data be the guide for any future action as it seeks to bring down inflation while supporting the labor market. "Looking forward, if the economy evolves broadly as expected, policy will move over time toward a more neutral stance. But we are not on any preset course," Powell told the National Association for Business Economics during a speech in Nashville. "The risks are two-sided, and we will continue to make our decisions meeting by meeting."

3. Ports on strike

East and Gulf Coast port workers are on strike. As of midnight, approximately 50,000 longshoremen walked off the job from 14 major ports spanning New England to Texas after the International Longshoremen's Association and the United States Maritime Alliance failed to reach a labor agreement. It's the union's first strike since 1977 and brought billions in trade to a screeching halt. "This is going down in history, what we're doing here," ILA president Harold Daggett told union members. "They can't survive too long."

4. Next steps

Time to put the best foot forward. Nike reports quarterly results after the bell Tuesday, weeks after the sneaker giant announced it would replace CEO John Donahoe. The company has been navigating a downturn in sales after a strategy to sell directly to consumers backfired. Weakened relationships with wholesalers cleared shelf space for upstart competitors like On Running and Hoka. Investors will be listening Tuesday for details on the executive transition, innovation and inventories.

5. Goal-setting

MLS is tackling a more global audience. The American soccer league is partnering with German digital media platform OneFootball to distribute highlights, stats and other MLS content globally. The agreement dovetails with the league's existing media rights deal with Apple and looks to build on the growing popularity of American soccer — boosted by superstar Lionel Messi. "In the U.S., with the arrival of Messi, the game has changed in terms of participation, in terms of awareness and in terms of fan interest," said OneFootball CEO Patrick Fischer.

– CNBC's Alex Harring, Hakyung Kim, Jeff Cox, Lori Ann LaRocco, Gabrielle Fonrouge and Lillian Rizzo contributed to this report.