That's a record closing high. April 4th's intra-day high of 16,631.63 is still a bit above today's intra-day high of 16,592.28.
The Trannies set their all-time intra-day and closing highs on April 23 at 7,814.92 and 7,742.26, respectively.
A Google news search
Update:
Oops, here's Dragonfy Capital:
Put Sonic On the Radar
The Dow Jones Industrial Average with a new all time high close just confirmed Dow Theory, joining the new high in the Transports. This has been 4 months in the making. What to do? Look for turn around stocks. One that I sold out of last month is Sonic....MOREStill nothing at Dow Jones however.