New Zealand insurer Tower Limited has no idea why its share price suddenly peaked earlier this month.

The company, which is listed on both the NZ and Australian stock exchanges, has been questioned by the Australian Stock Exchange (ASX) after a sudden increase in its share price.

In a statement of response to the ASX last week, Tower NZ said it could not identify any particular reason for the spike in stock between August 6 and August 19.

“We are not aware of any information concerning Tower that has not been announced to the market which, if known, could explain recent trading in the company’s shares,” it said.

“As you are aware, there has been a significant sale of shares in an unrelated company, Tower Australia, which may have led to some speculation in the marketplace.”

Tower Limited NZ shares rose 4.76% to $2.20 in afternoon trading on August 8 after UK-based investment company Guinness Peat Group – which also owns 35% of Tower Limited – sold its 29.7% key stake in Tower Australia for $375 million.

Dai-chi, Japan’s second-largest privately run life insurance company agreed to pay almost an extra $1 a share, or almost $100 million, to become a cornerstone shareholder in Tower.  

Tower demerged its NZ and Australian entities in November 2006.