I don't know if I should be worried or not - that's where my portfolio is.
Bear in mind that managing a portfolio and owning stock in Merrill Lynch are two different things. If you own a lot of Merrill Lynch stock, you may be in trouble although their stock increased today because of BOA buying them out. If ML is simply managing your investments - such as a 401k - it is doubtful that a large percentage of your investment is in ML stock. Typically a portfolio is diversified enough to prevent a huge hit if XYZ company crashes.