* HK regulator warns on Goldin Properties share structure
* Share price swings risk harming Hong Kong market image
* CFO says Goldin Properties in good financial health (Adds Goldin Properties comment)
By Elzio Barreto and Clare Jim
HONG KONG, June 8 (Reuters) - Hong Kong's securities regulator urged investors on Monday to exercise "extreme caution" in trading Goldin Properties Holdings Limited because the majority of the stock is held by a small group of investors, making it very volatile.
The notice from the Securities and Futures Commission (SFC) follows a warning late last month that urged investors to stay away from companies whose valuations bear little resemblance to their underlying business.
It also comes weeks after filings linked Goldin's sister company, Goldin Financial Holdings, to China-based Hanergy Thin Film Power Group Ltd, another large Hong Kong listed company with a concentrated shareholding whose share price fell dramatically in the span of one hour.
Dramatic price moves in the shares of Goldin and Hanergy risk undermining Hong Kong's reputation as a global financial hub at a time of increased interest from foreign investors following the launch of a Hong Kong-Shanghai trading link.
The link, launched in November, has brought in a flood of Chinese funds, but also made Hong Kong's market more volatile.
Goldin Properties sidestepped questions about whether affiliated companies were the cause of the concentrated shareholding mentioned in the SFC warning.
Chairman Pan Sutong controls 64.4 percent of shares, while a group of 13 shareholders owns another 30.75 percent, the SFC said in a statement. It did not give any individual names of who was in the group.
"We don't know who the 13 shareholders are SFC was referring to," chief financial officer Kenas Chan said on a conference call with reporters .
"Other than chairman Pan Sutong and directors, it's normally the major fund companies that are holding our shares."
The SFC issued a similar warning in March against Goldin Financial, also controlled by Pan, after its shares jumped more than 400 percent between September and March.
Goldin Properties shares had soared 450 percent over a two-month period between mid-March and mid-May, only to slump 48 percent between May 20 and 21 and bounce back up 73 percent in the following seven days, the regulator added.
Goldin's Chan said company chairman did not use shares as collateral for a loan and the company was in good financial health with no external loans.
Chan said the company was reviewing proposals to improve its shareholding structure but no decision has been made.
Hanergy, a $40 billion company controlled by Li Hejun, lost half of its value in less than an hour on May 20 and its shares have been halted since the plunge. (Reporting by Elzio Barreto and Clare Jim; Editing by Miral Fahmy and Keith Weir)