SINGAPORE (Reuters) - The family that owns Malaysian gaming firm Genting sold about 9 percent of shares in its Singapore unit to institutions on Wednesday, raising S$615 million, two sources with knowledge of the deal told Reuters.

A total of 853.8 million Genting Singapore shares were sold at S$0.72 a share, a discount of around 17 percent from its last closing price.

Shares of the firm dropped as much as 21 percent in early trade, inviting a query from the Singapore Exchange about the sharp movement in its share price.

Shares in Genting Bhd , which is controlled by the family of its Chairman and CEO Lim Kok Thay, were down 4.5 percent at 0218 GMT.

The shares were sold at the lower end of a price range of S$0.72-S$0.76 a share, listed in a term sheet seen by Reuters.

UBS and JPMorgan are joint book-runners for the secondary placement, the sources told Reuters.

The sale, through the family's vehicles Golden Hope Ltd and Lakewood Sdn Bhd, was aimed at boosting the liquidity of the stock, according to one of the sources.

Genting officials in Singapore and Malaysia declined to comment. The sources did not want to be identified because the deal is not public.

Both Golden Hope and Lakewood are vehicles linked to Lim, company documents show.

Genting Singapore, which also owns casino assets in Britain, is building the city-state's second casino that will open by the middle of 2010.

Genting Bhd, the holding company of the Lim family, has a 54.5 percent stake in the Singapore-listed arm while various family vehicles controlled around 9 percent of the firm before the sale, according to Thomson Reuters data.