The multifamily development flurry in Philadelphia has added nearly 11,400 new apartment rentals over the past 12 months, and nearly 80% of these new units fall into the high-end, four- and five-star-rated property category. As a result, the overall vacancy rate for this top-of-the-market segment reached 10.7% in the fourth quarter of 2023—double the vacancy rate for three-star and lower-rated apartment units.