https://www.oslobors.no/ob_eng/Oslo-Boers/Trading/Market-surveillance/Market-interference Special observation is a measure used under circumstances that may make the valuation of the security in question particularly uncertain. The fact that a security is placed under special observation does not in itself impose any restrictions on trading, but it serves to notify market participants that there is some particular uncertainty over the pricing of the security. Special observation can, in contrast to a matching halt, be applied for a longer period.