Updated

Netherlands-based Euronext has increased its offer to acquire the Oslo stock exchange, stepping up a bidding war with rival Nasdaq, which owns all the other bourses in the Nordic-Baltic region.

Euronext offered Monday 158 kroner ($18.25) per share, up from a previous bid of 145 kroner. It reportedly values the company at 6.79 billion kroner ($784 million) and is 6 kroner above the offer from Nasdaq, whose bid is due to expire at the end of the day.

Oslo Boers has indicated it prefers a deal with Nasdaq. Nasdaq already operates the main stock exchanges in Sweden, Denmark, Finland, Iceland and the three Baltic countries.

Euronext, which operates six exchanges in Europe, said the acceptance period was extended to March 11. It launched its first bid on Dec. 28.