You would look at the purchase and sale dates. January 1-January 1 equals one year and is short term. Long term is a year and a day.
The IRS classifies capital gains and losses on stock transactions as either long-term or short-term, depending on the length of time you owned the stock prior to the sale. If you owned your stock for one year or less prior to the sale, your gain or loss is short-term. A sales transaction for stock you have held for more than one year will result in a long-term capital gain or loss.