The company that runs Citi Bike is in advanced talks with an affiliate of a major real-estate developer about an investment that would fuel an expansion of New York City's bicycle-sharing program, according to people familiar with the negotiations.

Alta Bicycle Share Inc. of Portland, Ore., which runs Citi Bike, has been negotiating a deal with REQX Ventures, an investment firm formed by the upscale fitness center chain Equinox and its parent, Related Cos., these people said.

...