Its revenue is growing, however: Zulily saw $127 million in sales in the first half of 2012.
The company has 2.2 million active customers, with revenue per customer of $214. It stages 4,000 flash sales per day, according to the S-1.
The company, founded in 2009, has been valued at $1 billion and has received $139 million in venture capital funding.
Its IPO was initially filed confidentially with the SEC, a so-called "secret" IPO, for companies that have less than $1 billion in revenues.