Real estate startup Redfin is getting ready for an IPO

Online real estate brokerage Redfin has put the "for sale" sign on its own shares, filing the paperwork for an IPO late on Friday. 
Redfin is backed by some of Silicon Valley's biggest names, and plans to begin trading on the Nasdaq exchange under the ticker symbol "RDFN," it said in the S-1 filing with the SEC.
Redfin pegged the size of the offering at $100 million, though that number is likely just a placeholder that will be updated with the real, larger number as it moves closer to