None! A shark doesn’t have any bones in it’s body.
That doesn’t mean a shark doesn’t have a skeleton however. A shark is classed as a chondrichthyes fish who’s skeletons are very different from those of bony fish and terrestrial vertebrates. Sharks and other cartilaginous fish (including skates and rays) have skeletons made of cartilage and connective tissue.
Cartilage (found in the human ear) is flexible and durable while being about half the normal density of bone reducing the skeleton’s weight, saving energy.