premise: Makoto Fukuda, head of the finance ministry's insurance department, said Nissan Mutual Life's accumuluated losses were about 200 billion yen, exacerbated by recent declines in share prices. As a result, he said, unrealised gains on securities holdings at the end of March were zero.
  Speaking a separate news conference, Fukuda said heavy selling of high-yielding pension funds caused an "abnormal situation" in the company's financial condition. "This product has no problem but it is a problem with the way it was sold by the company," he said.
  Fukuda also said that the company's mutual ownership probably prevented it from boosting equity to deal with its difficulties.
   What caused the exacerbated losses for Nissan Mutual Life?
hypothesis: recent declines in share prices