Why Did Walter White Call Himself Heisenberg. Expanding the list in bizentass's comment (started as a comment of my own but then it got long): In the same way, gray matter company was way more successful than walter white but walter had more.
Knowing he’s close to death one way or the other, he is at last able to admit that heisenberg — rather than walter white — is his true persona. He announces himself as heisenberg, the name he will use as his criminal pseudonym when he gets to tuco’s office.