You suspect an irregular trade on the stock exchange

FINMA analyses any unusual movements in traded securities as part of its routine market supervision. We always scrutinise big losses or gains, major product volatility and high trading volumes. Following our initial enquiries, we will decide what action to take next, such as whether FINMA needs to pursue more detailed supervisory investigations or even initiate a procedure.

In the event of criminal activity, FINMA also informs the competent criminal authorities. Furthermore, FINMA is in close contact with the stock exchanges’ trading surveillance departments, which – within the context of self-regulation – monitor price formation on the stock exchanges, investigate irregularities and, if relevant under supervisory law, inform FINMA about such cases.

If you suspect an irregular trade on the stock exchange, you can tell FINMA. If your suspicion bears out, FINMA will exercise its supervisory powers to put an end to irregularities. However, as a general rule, FINMA is not able to comment on its ongoing supervisory activity or individuals. It is therefore not able to provide you with its assessment or inform you about any measures taken.
If you have suffered a financial loss after unaccountable movements in prices, we will not be able to help you. This is strictly a task for the courts.

You can find more information here.