UPDATE 1-German bank Comdirect Q2 profit falls, shares slide

(Adds CEO quote, analyst view, share price)

FRANKFURT, July 22 (Reuters) - Comdirect (CDBG.DE) reported weaker than expected second-quarter earnings on Tuesday, citing risk aversion among German retail investors, sending shares in the online bank lower.

Comdirect's April-June pretax profit fell to 12.8 million euros ($20.34 million) from 21.5 million euros a year earlier. The average pretax profit estimate in a Reuters survey of analysts was 14 million euros.

Chief Executive Michael Mandel said Comdirect, whose stock market-related activities focus mainly on domestic retail investors, does not expect any substantial increase in trading activity this year.

Instead of investing in equities, Comdirect clients were increasingly depositing funds in call money and check accounts.

"Taking this into account, we are satisfied with the first weeks of the third quarter," Mandel told Reuters.

Comdirect saw its customer numbers grow by one-fifth in the first half to 1.21 million. Assets under custody rose 7 percent to 21.7 billion euros, it said in a statement.

Net interest income rose 38 percent to 40.6 million euros but net commission income fell 23 percent to 29.3 million euros.

At 0935 GMT, Comdirect's shares traded 3.9 percent lower at 7.41 euros, while the DJ Stoxx European bank index .SX7P was off 2.4 percent.

DZ Bank analyst Werner Eisenmann said Comdirect's weak second-quarter results and the persistently difficult trading environment would prompt many analysts to cut their earnings estimates for the bank.

Mandel said Comdirect plans to expand into a full-service bank and would invest between 60 million and 70 million euros for that purpose this year, up from 50 million euros envisaged earlier. (Reporting by Philipp Halstrick, writing by Janice Sommer; editing by Sue Thomas)