Net profit attributable to shareholders was 310.9 million euros ($368 million), compared with 256.7 million euros a year ago, the company said. Analysts had expected a profit increase of 16%.
Low market volatility depressed revenue, and low interest rates kept a lid on interest income, the company said.
But recent acquisitions, such as the fund distributor platform Clearstream Fund Centre from UBS, as well as the purchase of Institutional Shareholder Services, helped buoy results.
"Especially in a cyclically challenging market environment like the second quarter of 2021, the importance of M&A growth becomes clear and confirms our strategy," said Chief Financial Officer Gregor Pottmeyer.
He said he was confident of reaching 2021 targets. They include revenue of around 3.5 billion euros and earnings before interest, taxes, depreciation and amortization of around 2 billion euros.
($1 = 0.8450 euros)
(Reporting by Tom Sims and Patricia Uhlig; Editing by Chris Reese and Mike Harrison)