Liquidnet said its trading volume moved 2 percent ahead of last year, with an 18 percent jump in June.

Overall, its block trading volume reached 7.0 billion shares, up from 6.9 billion, in the first half of 2010.

In June, volume reached 1.1 billion shares, up from 924,000 a year earlier, Liquidnet said.

Average daily volume in June was 49.5 million, up from 42.0 million.

Liquidnet typically handled 40 percent of the day’s market block volume in particular stocks, it said.

Average execution size in the second quarter was $1.3 million, up 37 percent from a year ago. In shares, the average execution size was 48,07, compared to 46,996 in the first half of 2010.

Internationally, total principal traded was $8.6 billion in the first half, compared to $6.7 billion a year ago, a gain of 27 percent.

The marketplace for institutions trading in equities in large sizes said it now reached into 39 countries, worldwide.

 “The safety, efficiency and global breadth of our deep pools of liquidity simply cannot be found elsewhere,'' said Seth Merrin, Founder and CEO of Liquidnet.