Elon Musk appears to have wrapped up a busy year of trading his Tesla shares Tuesday. He'll end up with one of the largest tax bills in history to show for it. The Tesla CEO exercised options to buy another 1.6 million shares, and sold 934,090 of those shares for $1 billion to cover the tax bite he'll be facing on that purchase. The trades completed the exercise of the 22.9 million options he held that were due to expire in August. He sold off 10.3 million of the shares he acquired thoughout the process to cover his tax withholding requirements. And he did it using a pre-arranged plan that allows company insiders to ... (full story)