SpaceX, the Hawthorne-based rocket company founded by billionaire Elon Musk, added $100 million in new funding to its recent haul, bringing the total raised since late July to $450 million, according to a Monday filing with the Securities and Exchange Commission.

The amended Series H round includes 25 unnamed investors and values Space Exploration Technologies Corp. at $21.5 billion, putting it among the world’s most valuable privately owned firms, according to Equidate, a marketplace for private company stock.

Last month, NASA awarded SpaceX a $97-million contract for a Sentinel-6A mission in 2020 aboard a SpaceX Falcon 9 rocket to study ocean topography and weather data.

Health business reporter Dana Bartholomew can be reached at [email protected]. Follow him on Twitter @_DanaBart.