NANOAOD: a new compact event data format in CMS

The CMS Collaboration has recently commissioned a new compact data format, named NANOAOD, reducing the per-event storage space requirement to about 1-2 kB. This represents a factor 20 reduction in storage space compared to the MINIAOD data format used previously for physics analysis at CMS. We envisage that the information stored in the NANOAOD data format is sufficient to support the majority of CMS physics analyses. NANOAOD also facilitates the dissemination of analysis methods and the automation of standard workflows for deriving conditions and object calibrations. The latest developments of this project will be presented.