Seattle-based Zulily says it is in talks to lease 230,000 square feet of office space in the Seattle Trade & Technology Center at 2601 Elliott Ave., and plans to vacate the Cobalt building in the SoDo neighborhood.

A Zulily spokeswoman said the company was “in final lease negotiations to take over 70 percent of the building currently occupied by RealNetworks,” which develops software for online audio and video.

Zulily is a fast-growing retail startup that markets discounted, limited-time offers targeted at moms, babies and kids. RealNetworks at one time occupied most of the 332,000-square-foot Trade & Technology Center, which is close to the waterfront between Vine and Cedar streets.

Several brokers said RealNetworks is downsizing to about 90,000 square feet at Home Plate Center in SoDo. Neither RealNetworks nor American Life, the developer of Home Plate, responded to requests for comment.

Sanjay Bhatt: 206-464-3103 or sbhatt@seattletimes.com On Twitter @sbhatt