TomTom took on a lot of debt to buy its mapmaker
Shares in TomTom were among the biggest fallers on Amsterdam's AEX after the satellite navigation firm revealed plans to issue new stock to raise cash.
The shares fell 5.1% after the company unveiled plans to raise 430m euros ($597m; £365m).
Of the new shares, 359m euros will be offered to existing shareholders while the rest will be sold to two investors.
TomTom has been struggling with the debt it took on when it bought digital mapmaker Tele Atlas for 2.9bn euros.
The sum to be raised amounts to almost half of the market capitalisation of the company.
TomTom shares rallied last week when it unveiled a navigation application for Apple's iPhone.
There were also rumours that Apple planned to take a stake in TomTom, although the company's chief executive said on Monday that there had been no approach from Apple.