Two national retailers will be moving onto posh Walnut Street, continuing what brokers say is the momentum of a healthy retail market.

In a deal that closed late Thursday but has yet to be announced, CB2, a furniture company described as the younger, hipper brother of Crate & Barrel, will be taking over the space occupied by Kenneth Cole, Lacoste, and a physical therapy office at 1422-24 Walnut St.

"It's a very prestigious furniture brand with a very modern design at a medium price point," said Andi Pesacov, senior vice president of retail services for Cushman & Wakefield, who represented both CB2 and landlord ASI Management in the transaction.

The CB2 store will be 12,000 square feet and will open in the fourth quarter of the year, according to Pesacov. It follows on the heels of another high-end furniture maker, Thos. Moser, moving into a showroom at 1605 Walnut St. last fall.

Pesacov said CB2 liked Center City demographics, which are trending younger with the influx of millennials and high-income professionals, and a much-improved retail scene with its mix of off-price retailers on Chestnut Street and luxury and high end on Walnut to attract a large, diverse pool of shoppers.

About two blocks away, UNTUCKit, a men's shop that sells button-down and other shirts meant to be worn untucked, debuted its 1,850-square-foot location at 1611 Walnut on Wednesday, a space formerly occupied by American Apparel.

"UNTUCKit's Philly arrival further validates that Walnut Street remains a vibrant retail corridor attracting those retailers that are current and actively expanding nationwide," said Brittany Goldberg, vice president at MSC Retail, who represented UNTUCKit in the deal. The landlord for the building is Pearl Properties.

The latest two national brands add to over 50 that have entered the city since 2014, according to the Center City District.

But the momentum has slowed a bit, said Jacob Cooper, partner and managing director at MSC.

"While Center City retail continues to thrive, we've seen some downward pressure on retail rents due to reduced demand from national apparel retail," Cooper said. "While there are still many darlings and new innovative companies like UNTUCKit and Warby Parker, many of the old stand-bys are slowing growth or even contracting, which increases supply and flattens rental rates."