Good news regarding Pfizer’s vaccine on Monday sent the market soaring, with the S&P 500 gaining over 1% to over 3,550 and the Dow Jones Industrials rising more than 800 points.

Unfortunately for clients of Fidelity, TD Ameritrade, Vanguard, Merrill Lynch, and Charles Schwab it was too much — all of these platforms experienced problems resulting in some people not being able to access their accounts.

The outages lasted hours.

One trading platform, conspicuously, seemed just fine. The formerly crash-prone Robinhood stayed strong throughout the day.

Over the past year Robinhood, the stock-trading upstart responsible for the extinction of brokerage trading commissions, went down at a few inopportune moments when the stock market was in action and people wanted access — and fast. (According to an August Bloomberg article, the Securities and Exchange Commission and the Financial Industry Regulatory Authority are investigating Robinhood’s handling of an outage in March.)

For Robinhood, a company that in some ways is like a startup but that has a huge influence and user base, it was a PR nightmare that cast a light on its rough edges.

The company seems to have learned from the mistakes however, and was prepared for volatility.

“This morning, despite historic traffic, Robinhood systems remained operational,” the company told Yahoo Finance. “Our engineering teams have worked diligently to harden our infrastructure, improve reliability, and increase capacity.”

Compared to say, Vanguard, Robinhood is a platform that many investors who trade frequently prefer because it’s easy to use and mobile-friendly. For this cohort, timing is everything — personal finance experts and Warren Buffett disagree — and many investors found themselves frustrated in the past.

Since outages earlier this year, Robinhood told Yahoo Finance that it’s invested considerably in its technology to make sure that its systems can handle the user load, especially during the busy days.

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Ethan Wolff-Mann is a writer at Yahoo Finance focusing on consumer issues, personal finance, retail, airlines, and more. Follow him on Twitter @ewolffmann.

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