NEW YORK CITY—Sales of US commercial property were running slightly ahead of 2006 levels at midyear, Real Capital Analytics reported late last week. Although the six-month dollar amount, $255.1 billion, suggests a  booming market, there's a big gap between the first and second quarters when it comes to year-over-year growth.

Q2's Y-O-Y gain was 23%, less than half the 49% increase this year's Q1 recorded over the same period in 2014. Taken together, the quarterly sales tallies put the first six months of 2015 ahead by 36%.

RCA describes the year-to-date sales volume as “front-loaded” in Q1, a term that applies both to sales of individual assets as well as portfolio and entity-level deals. “There are two ways to look at these shifts in the year,” according to RCA's US Capital Trends report. “A cautionary perspective would view this slowdown in growth with concern that investors are becoming hesitant about future trends in interest rates, what the Federal Reserve Bank will do in the fall, and how it will impact the property markets. A more optimistic view is that the 49% Y-O-Y growth in volume seen in Q1, had it continued, would have likely been the start of frenzied market with the potential for a bubble.”

However one looks at the Q2 dropoff, though, RCA notes that “the lower growth in volume has not been matched with increases in cap rates. so it is not as if investors are pulling away from commercial real estate.” Although the quarterly trend in volume warrants more attention, RCA says it should not make anyone lose sleep.

A closer look at the Q2 numbers reveals where the growth was as well as where cap rates were headed during the quarter. Among the strongest growth was in industrial, up 40% Y-O-Y. There again, however,  Q2 growth was off from the prior quarter—marked by entity-level deals such as the Global Logistics Properties/GIC acquisition of the IndCor platform—on a Y-O-Y basis, and RCA is also seeing a slowdown in cap rate compression for industrial product. Nonetheless, cap rates did narrow further during Q2, by 30 basis points to average 6.9%.

Similarly, hotel properties posted 43% Y-O-Y sales growth in Q2 to reach $26.9 billion. Yet this also represented a dropoff from Q1, when Y-O-Y growth was 94%. Hotels posted 67.5% sales growth for the first six months of this year, just behind industrial's 70% Y-O-Y gains.

Also front-loaded to Q1 was YTD sales growth in the multifamily sector. Apartments posted just 13% greater volume in Q2 this year than in the same period last year. Q1 accounted for the sector's 37.6% YTD improvement, with total sales for the first six months reaching $63.2 billion.

Across all sectors, RCA says, cap rates are averaging 6% nationally. And while price resistance by some buyers may be slowing volume growth, “the current level of activity is still high and indicative of healthy investor interest,” accord to the USCT report.

That being said, RCA notes that investors are growing concerned about “the similarities in the current market to those leading up to the last peak. Indeed, into Q2 cap rates are about the same or lower and volume is remarkably similar as well."