Investment sales had a slow first half this year in New York, with only one borough showing positive signs.

The city's investment sales consideration, or the total dollar value of all sales, for the first half was $18B, a 39% decrease from the first half of 2016, according to a Real Estate Board of New York report. The total number of transactions across the city decreased 6% year-over-year.

In Manhattan, the slowdown was even more deeply felt, with a 49% year-over-year decrease in sales consideration and a 8% drop in number of transactions. Manhattan accounted for 60% of the transactions citywide, the smallest share it has had since REBNY started tracking in 2014. The city's total sales consideration was also the lowest since tracking began.

The first half had the single biggest drop in sales consideration since 2014, an acceleration of the steady decline in investment sales in the city since the first half of 2015. Of all the boroughs, only Staten Island, which topped $300M in total sales consideration, improved year-over-year.

The largest transaction of the year has been Chinese investment company HNA Group's $2.2B purchase of the office tower at 245 Park Ave. from Brookfield Properties in March, followed by Singapore's sovereign wealth fund's buy into 60 Wall St. for $1B.