In spite of the market downturn, the trading services that Fidelity Investments provides for intermediaries is doing a brisk business, the company announced Thursday.

Daily average commissionable trade, new breakaway brokers joining the platform, equity order flow, prime brokerage and adviser-sold 401(k) plans are all doing well. Combined, the divisions serving these markets had $1.1 trillion in assets under administration by the end of last year.

Daily commissionable trades rose 18% in 2008 and averaged 259,000 and 314,000 in September and October. Fidelity also sold 702 new Fidelity Advisor 401(k) plans in 2008, up 36%. Money market assets rose 44% to a record $137 billion, and 102 breakaway brokers selected Fidelity as custodian.

Assets in Fidelity’s prime brokerage services also rose, by 127%, aided by a 57% increase in new clients.

“Despite arguably one of the most volatile business environments in recent memory, we repeatedly demonstrated our ability to help intermediary clients navigate challenging financial markets,” said Michael K. Clark, president of Fidelity Institutional Products Group. “Our ability in 2008 to achieve record trading volumes, equity order flow and institutional money market flows, among others, was a direct result of the trust our diverse base of clients placed in the strength and reputation of Fidelity,” Clark added.

Even in this challenging market environment, Fidelity plans to continue to invest in these businesses’ technology, trading tools and services in 2009.

“We are in an unprecedented business environment that is rapidly transforming the financial services industry, and those firms which do not have all the pieces to serve these converging markets and new financial business models will be at a competitive disadvantage,” Clark said.