On May 22, 2018, Judge Victor Marrero of the SDNY issued an order winding up In Re: Municipal Derivatives Antitrust Litigation, 1:08-cv-02516-VM-GWG). This multi-district litigation was a 2008 case; the cases that were combined in the multi-district litigation likely were from even earlier.
The reasons complex litigations such as these take so long are many and complicated. I leave it to others to debate the merits of those reasons. If you are going to engage in such litigation, know that it may not be a swift process.