The Federal Reserve reports its balance sheet has topped $4 trillion for the first time ever. The Fed's $85 billion-a-month bond purchases have really been adding up in what is the third round of quantitative easing. The Fed announced they'll be trimming those purchases by $10 billion starting next month. Stepping back, some economists are worried it may be hard for the central bank to shrink that balance sheet at some point without disturbing financial markets. So we want to know from you: How concerned are you about the Fed's $4 trillion balance sheet? Vote your thoughts below and leave a comment as well.