YC doesn't hold shares in Cruise anymore, since the company as a whole was sold to GM for 1 billion in 2016. After the acquisition, GM invested another 1.1 billion, Softbank Vision Fund invested 2.25 billion and now Honda invests 2.75 billion. So more than 7.1 billion dollar has been invested into Cruise. It's the best capitalised YC company. Airbnb has raised 4.4 billion, debt financing included.