Interactive Brokers(NASDAQ:IBKR) had good reason to celebrate this past Memorial Day. The company's key metrics for May were generally higher on both a month-over-month and an annual basis. According to the company's data, its daily average revenue trades, or DARTs -- considered by many to be the most critical figure in the discount brokerage industry -- were roughly 509,000. That's 13% higher when compared with May 2012, and 6% above the preceding month's level.

Also seeing a rise was end-of-month customer equity, which came in at $37.9 billion, 37% higher than at the same time in 2012, and 4% above April's figure.

Ending customer credit balances grew 27% on a year-over-year basis to $22.7 billion, although that number is essentially flat compared with the prior month.

Fool contributor Eric Volkman has no position in Interactive Brokers. The Motley Fool recommends Interactive Brokers. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.