The volatile session came after the company’s fourth-quarter results missed analysts’ expectations. The brokerage, used by individual investors, recorded revenue of $363 million for the October-through-December period, an increase of 14%. Analysts polled by FactSet expected quarterly revenue of $376 million and a net loss of $225 million.

For the year, Robinhood recorded an 89% jump in revenue to $1.82 billion, compared with $959 million the previous year. Its net loss totaled $3.7 billion for the year.

The company had an increase in technology and administrative expenses that ate into its results.

Revenue tied to options and cryptocurrency trading picked up in the latest quarter from a year earlier, reflecting individual investors’ willingness to dabble in riskier and more speculative trading strategies in 2021. Revenue tied to customers’ options trading rose 14% to $163 million.

The company said fourth-quarter revenue tied to stock trading fell 35% to $52 million from $80 million in the same quarter of 2020, the period before individual investors stormed the markets in January 2021 to wage a guerrilla-style warfare against hedge funds.

Robinhood became a darling of the Covid-19 era, as millions of new investors began trying their hand at trading. The brokerage now has 22.7 million customers with funded accounts, it said Thursday, up from 12.5 million in 2020.

The company faces stiff competition. Larger asset managers such as Fidelity Investments and

BlackRock Inc.

have used their size to increase profits even while cutting fees. They have also focused on adding products with higher fees.

Robinhood started the first half of 2021 in a strong position as millions of investors entered the market to trade meme stocks such as

GameStop Corp.

and cryptocurrencies such as dogecoin. Yet as the year went on, it was hard to keep the momentum. The company has experienced a slowdown in revenue tied to customers’ trading. Revenue tied to cryptocurrency trading was particularly hard hit in the third quarter. That trend continued in the fourth quarter, with revenue tied to cryptocurrency trading falling roughly 5.9% compared with the July-through-September period.

The new year hasn’t provided relief, with trading continuing to fall, the company said.

Robinhood said it expected first-quarter revenue of less than $340 million, a number that would represent a 35% year-over-year decline.

Jason Warnick,

Robinhood’s chief financial officer, said in a call with the media that trading activity has picked up in recent days.

Mr. Warnick said the company is planning to roll out products that focus on longer-term investing. He said that the company expects to begin introducing tax-advantaged retirement accounts midyear and that there is an opportunity to expand internationally—particularly in the cryptocurrency space.

The company this month started rolling out cryptocurrency wallets to some customers, he said. The move allows those customers to move their crypto holdings in and out of the Robinhood app.

Robinhood’s stock has been punished lately as investors rotate out of growth companies that were popular last year. Robinhood has lost about 67% from its initial public offering price of $38 a share.

Write to Caitlin McCabe at caitlin.mccabe@wsj.com