The concerns of downtown Chicago multifamily heading toward a bubble grow by the day with a packed pipeline, and new rent numbers will feed that fear.

CoStar market economist Brandon Svec analyzed downtown rent numbers for Bisnow. Since the beginning of Q3, rents in Class-A properties downtown have fallen by more than 6%. Properties delivered in the last cycle and earlier during this cycle are performing worse, which speaks to new properties cannibalizing the tenants of properties delivered earlier in the cycle.

Svec's analysis also identified a cyclical trend with rents the past three years. Where the first half of a year saw rent increases, the last six months saw declines in rent. For 2017, the decline in rents in Q3 and Q4 effectively wiped out any gains in Q1 and Q2, meaning rents to date are negative over the same time frame last year. With over 8,500 new apartments being added to the downtown inventory through 2019, it will be interesting to see if the momentum in downtown multifamily will continue next year.