Intraday Data Aggregation

I have intraday 1-minute data and my intraday bars show the "start time of interval". I am showing only the day session and the first bar starts at 9:30. However, the last bar has a time of 4:00 PM. From my understanding, the last bar represents the trades at 4:00 PM on the dot since that is the exact close. Am I understanding that correctly? If this is correct, is there a way to aggregate the trades at 4:00 PM with the prior bar?