Treasury Secretary Timothy F. Geithner said bank regulators should take the time they need to get the Volcker rule ban on proprietary trading right.

“Part of the challenge is people want things that are simple, but it’s not a simple thing to say to -- try to draw those lines between market making and other forms of trading,” Geithner said Thursday in an event at the Dallas Regional Chamber. “There’s absolutely some work to do on this.” Geithner was in the Dallas area to meet with local business leaders and tour a railway facility.

The Volcker rule, named for its original champion, former Federal Reserve Chairman Paul Volcker, is intended to reduce the chance that banks will make risky investments with their own capital that put depositors’ money at risk. The provision is part of the Dodd-Frank Act of 2010.