Shares in the aircraft maintenance company SIA Engineering fell as much as 9 percent to S$3.15 on Wednesday amidst heavy trading.
About 4.3 million shares worth about S$15 million changed hands, making the stock the fifth-most active counter by traded value.
Singapore Exchange has issued a query to the company to explain the unusual trading activity. SIA is yet to respond to it.
SIA Engineering on Tuesday said it has set up a joint venture with aircraft designer Moog Inc to provide component repair services to Asia Pacific and beyond.
SIAEC will have 49 percent equity stake in the Singapore-based JV called Moog Aircraft Services Asia Pte Ltd, while Moog will hold the remaining 51 percent, it said in a statement.
SIA Engineering provides airframe and component overhaul services, line maintenance and technical ground handling services.
It also manufactures aircraft cabin equipment, refurbishes aircraft galleys, repairs and overhauls hydromechanical aircraft equipment.
At 0250 GMT, SIA Engineering was trading down 4.9 percent at S$3.29. Shares in the company have lost 1 percent so far this year, giving it a market value of S$3.9 billion.