• The Supreme Court suggested the Federal Reserve has special protections.
• Hinge Health debuted on the NYSE in its IPO.
• The Treasury Department is set to halt penny production.

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

1. One down

The Dow Jones Industrial Average slipped only one point on Thursday and the S&P 500 was also essentially flat as investors worried about rising rates and a growing U.S. deficit. The Nasdaq Composite advanced 0.28% for the day. Meanwhile, the 30-year Treasury bond hit levels not seen since 2023 as lawmakers passed a bill that includes lower taxes and additional military spending, raising concerns about the country's debt level. Follow live market updates.

2. Fed reserved

The Supreme Court suggested that members of the Federal Reserve have stronger protections than other federal agencies' boards that would prevent them from being fired by the president. "The Federal Reserve is a uniquely structured, quasi-private entity that follows in the distinct historical tradition of the First and Second Banks of the United States," the majority ruling said. In a 6-3 ruling in which the liberal justices dissented, the court allowed President Donald Trump to fire Gwynne Wilcox from the National Labor Relations Board and Cathy Harris from the Merit Systems Protection Board while their lawsuit challenging their terminations is still pending.

3. Hinge prompts

Shares of Hinge Health rose 17% in their debut on the New York Stock Exchange, bringing the market capitalization for the digital physical therapy company to more than $3 billion. The company raised roughly $273 million in its initial public offering after selling shares toward the top end of its expected range. The broader IPO market has been in an extended drought since the end of 2021, but Hinge is betting that Wall Street is ready to back a new digital health offering.

4. UnitedHealth's face

In many ways, UnitedHealthcare has become the face of America's health insurance frustrations and its complicated health-care system. Its company, UnitedHealth Group, is the biggest in the insurance industry by market cap by far, worth nearly $275 billion, and it serves more than 29 million Americans. Experts say its size means it's no surprise that the company often faces public and political scrutiny. CNBC spoke with health policy experts, patients and UnitedHealth Group employees about how the company got so powerful.

5. Pennies on the dollar

Get ready to round up: As it becomes more expensive to mint the smallest U.S. coin, the Treasury Department has ordered its last batch of "blanks" it uses to make the penny, a spokesman said. That means the last batch of new pennies will enter circulation next year and that the coin will eventually be phased out. Businesses will likely have to round up the costs of goods to the nearest dollar. The move comes as Trump has looked for ways to cut spending deemed unnecessary, and the Treasury estimates halting the production of pennies will save $85 million.

— CNBC's Lisa Kailai Han, Dan Mangan, Ashley Capoot, Annika Kim Constantino and Jeff Cox contributed to this report.