Something is going on
When such an important number of domain names are registered at the same time, it means that there is something going on...or maybe there was a fantastic communication campaign in China and all LTD companies decided to grab their ".ltd" domain name...but I doubt it. It is also possible that an investor decided to focus on this Top-Level Domain.
Just for the note
The "LTD" is the sign for Limited Companies (limited company). There is a .LTDA new gTLD too which was delegated in 2014. The registry says that ".LTDA domains are only available to companies which are recorded as Sociedad de Responsabilidad Limitada or Sociedade Limitada at the responsible authorities in Brazil and other Latin American countries".
When choosing a domain name, I strongly suggest to check that document first, it is the list of similar domain name extensions.