Helen holds 1,000 shares of Fizbo Inc. stock that she purchased 11 months ago. The stock has done very well and has appreciated $20/share since Helen bought the stock. When sold, the stock will be taxed at capital gains rates (long-term rate is 15% and short-term rate is the taxpayer's marginal tax rate). If Helen's marginal tax rate is 35%, how much would she save by holding the stock an additional month before selling? What might prevent Helen from waiting to sell?