According to Finnish newspaper Helsingin Sanomat, Elop wasn't allowed to trade the shares. Nokia informed the paper that after Elop started planning the co-operation with Microsoft, trading away the Microsoft stock and buying Nokia stock instead would have been considered illegal due to insider information.
A poor translation of the article is as follows:
On Saturday, Nokia informed Helsingin Sanomat that the CEO of Nokia, Stephen Elop, doesn't own any Nokia shares yet due to stock market regulations. The same reason has prevented Elop from selling his remaining Microsoft shares.
Stock market regulations prevent company insiders from using unreleased insider information in their trades. According to Nokia's interpretation, the changes in strategy that Elop planned were considered insider information until last Friday.
When Elop started his work on 21st of September, he also started to plan the new strategy. Nokia informed the because of this, Elop hasn't been able to buy shares.
According to Nokia, Elop had to stop selling his Microsoft shares last year for the same reason. According to Nokia's information, Elop was able to sell 60 percent of his Microsoft shares which means he still has 40 percent left to sell.
Elop stopped selling his Microsoft shares when significant co-operation with Microsoft was brought into the plans.
Nokia doesn't publish the date when that happened, but according to information from Nasdaq, Elop sold 23 000 Microsoft shared on the last day of previous August.
He still has 261 000 Microsoft shares.