For completeness, on ewams' question: if the options are non-qualified (NQSO instead of ISO) and FMV at the time of exercise was $500, you would owe ordinary income tax on $400 ($500-$100) of income in 2015 tax year and long-term capital gains on $500 ($1000-$500) in 2017 tax year.
Not a tax pro; this is not tax advice; yada yada.