Many of the above comments are correct about illiquidity. If someone needs to trade at a time of low liquidity, for instance when the markets are closed, the bid/ask spread can often be large to induce someone to trade at odd times. Especially as the broker/bank on the other side of the trade can't immediately go to the market to close out the risk as they often prefer to do.
In this case the jump is actually is large but not that large (~4%). Note this trade price is near the close price on the day before.
The system I use shows a trade that evening for 5 shares near the price on the graph. If you called me after I was done with work and tried to buy 5 shares I'd quote you a bad price too.