Dive Brief:

• Shein could reach a $100 billion valuation if the Chinese fast-fashion retailer completes the $1 billion investment it's reportedly pursuing, according to unnamed sources cited by Bloomberg on Sunday.

• The apparel e-retailer is in the midst of meeting with potential investors, including growth equity firm General Atlantic, according to the Bloomberg report. General Atlantic declined to comment to Retail Dive; Shein didn't immediately return a request for comment.

• Belying the notion that fast fashion is declining, and surpassing rival Gen Z favorites like Asos and Boohoo Group, Shein's revenues last year rose 57% to some $15.7 billion, according to estimates from Coresight Research.

Dive Insight:

As fast-fashion stalwarts like H&M and Zara have had to confront rising consumer demand for more sustainably made clothing and some indications that younger consumers are less motivated by style trends, Shein has captured market share with what may be one of the fastest production cycles ever.

The online retailer reaches its target shoppers on social media and offers a level of newness that entails "analyzing customer data to inform new designs within as little as three days" and adding more than 1,000 new styles daily, according to research from retail analytics firm Edited. Shein is poised to grab even greater fast-fashion market share in the U.S. this year, according to a report on the company from Coresight, which cites its "real-time retail model, competitive pricing and aggressive social media strategies."

Shein ranks 12th in the U.S. for "most shopped" retailer of apparel and footwear, with 12% of apparel shoppers reporting that they had purchased from Shein in the past 12 months, outpacing specialty retailers including American Eagle, Gap, H&M, Lululemon, Victoria's Secret and Zara, and department stores including Nordstrom, according to Coresight. Among younger consumers, that's even higher, at 22%.

Still, Shein does have its challenges, according to that report. Shein isn't competitive when it comes to delivery, which Coresight calls "one of the major drivers of enhancing customer engagement."

And its fast-fashion reputation carries a downside, with Coresight noting that, "Ensuring ethical and sustainable sourcing will also be a key challenge for the company."  Last year, in a sustainability report, Shein said it is working to limit its environmental impact, with CEO Chris Xu pledging to "collaborate with governments, civil society and NGOs to drive systemic change."