If you're worried about taxes, selling might incur even more taxes. If your $10,000 investment went up to $14,000 and you sell, then then owe $4,000 in capital gains. Hopefully you held more than 366 days and can use the lower long-term capital gains rate (15% for most people). But that still leaves you paying maybe $600 of taxes on $4k of gains if you sell. At Vanguard, go to the "cost basis" area of your account and you can see how much unrealized gains will be realized when you sell.