Singapore-listed investment holding company Blumont Group halted trading in its shares for an hour and a half on Tuesday morning after being queried by the Singapore Exchange (SGX) over an unusually steep rise in its share price.

SGX noted that Blumont's share price has risen from 30 cents on Jan 2 this year to $2.45 as at Sept 30.

"This is an eight-fold increase over only nine months," the SGX said, adding that Blumont's market capitalisation has jumped over the same period from $508 million to $6.3 billion - a 12.5 fold increase.

While Blumont has announced a series of acquisitions since December last year, most were relatively small and "these announcements may not sufficiently explain the steep increase in the price of Blumont shares", the SGX said.

Further, it noticed that after Blumont announced a rights issue on July 29, the price of its rights shares - which started trading on Sept 26 - rose from $2.10 to $2.57, exceeding Blumont's share price, which increased to $2.45.

The SGX asked if Blumont was aware of any information not previously announced but that might explain the steep increase in the share price, or if it was aware of any other possible explanation for the unusual trading activity.

In response, Blumont said it was not aware of any such information or any other explanation for its share price jump.

"Save for the transactions previously announced by the company, the company is not aware of any other possible explanation for the trading," it said.

Blumont added that it is "constantly in discussions with various parties" on corporate development opportunities but that "these opportunities are still preliminary and no definitive agreements have been executed... in any event, there is no certainty that any of these discussions will materialise".

Blumont halted trading in its shares at 10.51am following the SGX query and resumed trading at 12.21pm after issuing its response to SGX.