TD Ameritrade  (AMTD - Get Report)  revenue jumped in the three months through March, as client trades surged despite gyrating financial markets that curbed earnings at the country's largest banks.

Total sales of $846 million also benefited from a 25 basis-point increase in interest rates in December, the first since the Federal Reserve cut them to nearly zero during the financial crisis of 2008. Net income climbed 8% to $205 million, or 38 cents a share, in line with analysts' estimates.

The Omaha, Neb.-based firm reported average client trades of 509,000 a day, an activity rate of 7.6%, which executives said was a record. 

"It was a volatile start to the calendar year and as a result, a strong quarter for trading, which was at record levels," CEO Fredric Tomczyk said on an earnings call.  "Strong trading plus the Fed Funds increase combined with strong organic growth drove record overall revenue."  

Net client assets at the online brokerage increased by $14 billion for a growth rate of 8%, another record. Total client assets are $711 billion. 

In Barron's 2016 online broker survey, TD Ameritrade was named the "Best for Novices" and the "Best for Long-term Investing," titles the company has held for the last four years.

The bank will focus in the remainder of the fiscal year, which ends in September, on maintaining momentum and aligning its business model with a new Labor Department rule that requires financial advisers to act in clients' best interests rather than merely providing "appropriate" advice, Tomczyk said.

The company's shares dropped 2.1% to $30.98 on Tuesday; TD Ameritrade has declined 11% so far this year.

"We continue to believe that our business model is in a relatively good position, not only to comply, but to identify opportunities in this new environment," he said. "We remain supportive of the Labor Department's intent in creating this rule, that advisers act in the best interest of their clients when giving investment advice in retirement accounts."

Like rival Charles Schwab (SCHW - Get Report) , TD Ameritrade stands to be hurt less by the rule than traditional wealth management firms since some of its funds let users move money around by themselves.

The rule, set to take effect in June, is designed to curb risks to consumers including retirees that arose during a broad shift from traditional company pension plans, which were more tightly regulated, to 401(k) and individual retirement accounts, whose advisers didn't have to meet the same requirements.

By classifying all such advisers as so-called fiduciaries, the Labor Department  said the new rule closed a loophole that had allowed some to "give imprudent and disloyal advice; steer plans and individual retirement account owners to investments based on their own, rather than their customers' financial interests; and act on conflicts of interest in ways that would be prohibited."