• Marqeta shares plummeted in extended trading on Monday after the company issued guidance that fell short of analysts' estimates.
• The stock was already down 15% for the year prior to the report and has lost more than 80% of its value since peaking in 2021.
• Revenue for the third quarter came in just shy of estimates.

Marqeta shares tumbled more than 30% in extended trading on Monday after the company issued weaker-than-expected guidance for the fourth quarter.

Here's how the company did compared with Wall Street estimates, based on a survey of analysts by LSEG:

• Loss per share: 6 cents adjusted vs. a loss of 5 cents expected
• Revenue: $128 million vs. $128.1 million expected

While third-quarter results showed a slight disappointment on the top and bottom lines, Marqeta's forecast for the current period was more concerning.

The payment processing firm said revenue in the fourth quarter will increase 10% to 12% from a year earlier. Analysts were looking for growth of more than 17%, according to LSEG.

Marqeta, which primarily functions as a card-issuing platform, attributed the guidance miss to "heightened scrutiny of the banking environment and specific customer program changes." The company has been struggling for a while, and its stock is now down more than 80% from its peak in 2021, the year it went public. The stock was down 15% for the year prior to the report.

Total processing volume of $74 billion was up more than 30% from a year earlier. Net revenue and gross profit were up 18% and 24%, respectively.

Marqeta's digital commerce business sells payment technology designed to detect potential fraud and ensure that money is properly routed. It also issues customized physical cards that look like a credit or debit card that can be used for point-of-sale purchases.

The company has been trying to break into the buy now, pay later business with a recently launched product called Marqeta Flex. The service brings BNPL from lenders such as Affirm or Klarna to any credit card wherever Mastercard and Visa are accepted.

"It's an orchestration layer, but it's tied to issuing and processing and disputes and chargebacks," CEO Simon Khalaf told CNBC at Money2020 in Las Vegas last week. "So it is not actually a Wild West in BNPL. It is actually very well established. And there is a reason why a lot of people are jumping to it."

WATCH: Marqeta CEO on Q2 earnings