Wells Fargo (WFC.N) is closing down its alternative trading system, or “dark pool,” due to decreased customer demand, the company said on Thursday. The San Francisco-based bank will still offer its clients a full suite of electronic trading tools to help them execute orders, but will stop offering access to the company’s dark pool on Friday, a spokeswoman from the bank told Reuters. Dark pools are electronic broker-run electronic trading venues, and every big bank has one.