Hit an iceberg, taking on water, and nothing can stop it from sinking. The bow is being pulled under by the weight of the water inside, and the watertight bulkheads do not extend far up enough to save the ship.
Titanic split before sinking; JANA wants to split Qualcomm. The bow section is QCT, the stern section is QTL. QTL will float for a bit longer than QCT, but in the end, both pieces are going straight to the bottom.