The U.S. Food and Drug Administration on Tuesday published a warning letter addressed to the wrist wearable company Whoop, alleging it is marketing a new blood pressure feature without proper approvals.

The letter centers around Whoop’s Blood Pressure Insights (BPI) feature, which the company introduced alongside its latest hardware launch in May.

Whoop said its BPI feature uses blood pressure information to offer performance and wellness insights that inform consumers and improve athletic performance.

But the FDA said Tuesday that Whoop’s BPI feature is intended to diagnose, cure, treat or prevent disease — a key distinction that would reclassify the wellness tracker as a “medical device” that has to undergo a rigorous testing and approval processes.

“Providing blood pressure estimation is not a low-risk function,” the FDA said in the letter. “An erroneously low or high blood pressure reading can have significant consequences for the user.”

A Whoop spokesperson said the company’s system offers only a single daily estimated range and midpoint, which distinguishes it from medical blood pressure devices used for diagnosis or management of high blood pressure.

Whoop users who purchase the $359 “Whoop Life” subscription tier can use the BPI feature to get daily insights about their blood pressure, including estimated systolic and diastolic ranges, according to the company.

Whoop also requires users to log three traditional cuff-readings to act as a baseline in order to unlock the BPI feature.

Additionally, the spokesperson said the BPI data is not unlike other wellness metrics that the company deals with. Just as heart rate variability and respiratory rate can have medical uses, the spokesperson said, they are permitted in a wellness context too.

“We believe the agency is overstepping its authority in this case by attempting to regulate a non-medical wellness feature as a medical device,” the Whoop spokesperson said.

High blood pressure, also called hypertension, is the number one risk factor for heart attacks, strokes and other types of cardiovascular disease, according to Dr. Ian Kronish, an internist and co-director of Columbia University’s Hypertension Center.

Kronish told CNBC that wearables like Whoop are a big emerging topic of conversation among hypertension experts, in part because there’s “concern that these devices are not yet proven to be accurate.”

If patients don’t get accurate blood pressure readings, they can’t make informed decisions about the care they need.

At the same time, Kronish said wearables like Whoop present a “big opportunity” for patients to take more control over their health, and that many professionals are excited to work with these tools.

Understandably, it can be confusing for consumers to navigate. Kronish encouraged patients to talk with their doctor about how they should use wearables like Whoop.

“It’s really great to hear that the FDA is getting more involved around informing consumers,” Kronish said.

Whoop is not the only wearable manufacturer that’s exploring blood pressure monitoring.

Omron and Garmin both offer medical blood pressure monitoring with on-demand readings that fall under FDA regulation. Samsung also offers blood-pressure-reading technology, but it is not available in the U.S. market.

Apple has also been teasing a blood pressure sensor for its watches, but has not been able to deliver. In 2024, the tech giant received FDA approval for its sleep apnea detection feature.

Whoop has previously received FDA clearance for its ECG feature, which is used to record and analyze a heart’s electrical activity to detect potential irregularities in rhythm. But when it comes to blood pressure, Whoop believes the FDA’s perspective is antiquated.

“We do not believe blood pressure should be considered any more or less sensitive than other physiological metrics like heart rate and respiratory rate,” a spokesperson said. “It appears that the FDA’s concerns may stem from outdated assumptions about blood pressure being strictly a clinical domain and inherently associated with a medical diagnosis.”

The FDA said Whoop could be subject to regulatory actions like seizure, injunction, and civil money penalties if it fails to address the violations that the agency identified in its letter.

Whoop has 15 business days to respond with steps the company has taken to address the violations, as well as how it will prevent similar issues from happening again.

“Even accounting for BPI’s disclaimers, they do not change this conclusion, because they are insufficient to outweigh the fact that the product is, by design, intended to provide a blood pressure estimation that is inherently associated with the diagnosis of a disease or condition,” the FDA said.

WATCH: Watch CNBC’s full interview with FDA commissioner Dr. Marty Makary

As Amazon chases SpaceX in the internet satellite market, the e-commerce and computing giant is now counting on Elon Musk’s rival company to get its next batch of devices into space.

On Wednesday, weather permitting, 24 Kuiper satellites will hitch a ride on one of SpaceX’s Falcon 9 rockets from a launchpad on Florida’s Space Coast. A 27-minute launch window for the mission, dubbed “KF-01,” opens at 2:18 a.m. ET.

The launch will be livestreamed on X, the social media platform also owned by Musk.

The mission marks an unusual alliance. SpaceX’s Starlink is currently the dominant provider of low earth orbit satellite internet, with a constellation of roughly 8,000 satellites and about 5 million customers worldwide.

Amazon launched Project Kuiper in 2019 with an aim to provide broadband internet from a constellation of more than 3,000 satellites. The company is working under a tight deadline imposed by the Federal Communications Commission that requires it to have about 1,600 satellites in orbit by the end of July 2026.

Amazon’s first two Kuiper launches came in April and June, sending 27 satellites each time aboard rockets supplied by United Launch Alliance.

Assuming Wednesday’s launch is a success, Amazon will have a total of 78 satellites in orbit. In order to meet the FCC’s tight deadline, Amazon needs to rapidly manufacture and deploy satellites, securing a hefty amount of capacity from rocket providers. Kuiper has booked up to 83 launches, including three rides with SpaceX.

Space has emerged as a battleground between Musk and Amazon founder Jeff Bezos, two of the world’s richest men. Aside from Kuiper, Bezos also competes with Musk via his rocket company Blue Origin.

Blue Origin in January sent up its massive New Glenn rocket for the first time, which is intended to rival SpaceX’s reusable Falcon 9 rockets. While Blue Origin currently trails SpaceX, Bezos last year predicted his latest venture will one day be bigger than Amazon, which he started in 1994.

Kuiper has become one of Amazon’s biggest bets, with more than $10 billion earmarked for the project. The company may need to spend as much as $23 billion to build its full constellation, analysts at Bank of America wrote in a note to clients last week. That figure doesn’t include the cost of building terminals, which consumers will use to connect to the service.

The analysts estimate Amazon is spending $150 million per launch this year, while satellite production costs are projected to total $1.1 billion by the fourth quarter.

Amazon is going after a market that’s expected to grow to at least $40 billion by 2030, the analysts wrote, citing estimates by Boston Consulting Group. The firm estimated that Amazon could generate $7.1 billion in sales from Kuiper by 2032 if it claims 30% of the market.

“With Starlink’s solid early growth, our estimates could be conservative,” the analysts wrote.

WATCH: Amazon launches first Kuiper internet satellites into space

Bitcoin fell below the $117,000 level on Tuesday after cryptocurrency-related bills were blocked in the House of Representatives.

The price of bitcoin was last down 2.8% at $116,516.00, according to Coin Metrics. That marks a pullback from the day’s high of $120,481.86.

The drop comes on the heels of multiple crypto-related bills failing to overcome a procedural hurdle in the House, with 13 Republicans voting with Democrats to block the motion in a 196-223 vote.

In recent days, bitcoin has been trading at all-time highs, spurred by institutional buying of bitcoin exchange-traded funds (ETFs) amid rising optimism that Congress would soon pass crypto legislation.

Stocks linked to crypto also came under pressure in late afternoon trading. Shares of bitcoin miners Riot Platforms and Mara Holdings closed down 3.3% and 2.3%, respectively. Others like crypto trading platforms Coinbase slid 1.5%. All were under pressure in extended trading.