I need some helpful info about earnings pre-warnings.

Why some (a few, not many, thanks God) public companies anounce pre-warnings of earnings miss about 2 weeks to one month before official date? It can cause double crashes of share prices. This action doesn't make sense and totally unnecessary and fails investors/traders taking hedging strategies before official announcement dates. Are there any SEC regulations requiring them do this or they have their own specific reasons for this?

Any thoughts are sincerely appreciated.