To the surprise of absolutely no one, AJ Styles retained the WWE Championship at Extreme Rules . As of this writing, he has been WWE Champion 254 days and counting, putting him at No. 16 on the list of longest WWE Championship reigns.
— WWE (@WWE) July 18, 2018 
Reminder: Styles has been in WWE for just 2.5 years, making this stat all the more eye-popping.
However, while the above infographic is impressive, Reddit user BITW44 looked at the stats  and pointed out that Styles could hit some seriously phenomenal milestones if he somehow manages to retain the WWE Championship through WrestleMania 35 in New York City.
All The Records AJ Styles Could Break – And How Likely They Are To Happen
The WWE Championship records AJ Styles  stands to surpass are as follows:
- If he retains at Hell in a Cell, nine days later he will surpass CM Punk (435 days)
- If he retains at Survivor Series, he will move into the top 10 longest combined reigns of all time, surpassing Randy Savage (520 combined days) and Stone Cold Steve Austin (530 combined days)
- If he makes it to WrestleMania 35 as champion, he will become the 7th longest reigning champion by combined days, surpassing Brock Lesnar (578 combined days), Triple H (610 combined days), and Bret Hart (655 combined days)
Those are some huge names that Styles could overtake. But how likely is that the Phenomenal One will beat those records?
In my personal opinion, it’s very likely that WWE will have Styles surpass CM Punk as the longest reigning WWE Champion of the modern era – and for several reasons.
First, the apparent reason: more than four years after Punk’s abrupt departure from WWE, the two sides have yet to reconcile. Even though Vince McMahon has reportedly said that Punk is welcome back in his company, there remains nasty blood  between Punk and McMahon’s heir apparent, Triple H. It would not surprise me at all if and when WWE has Styles surpass Punk to prove a point.
Second, up until very recently, Styles’ name was synonymous with TNA. While the rivalry between WWE and TNA is absolutely nothing like it used to be, it would be a major power play on WWE’s part to make AJ Styles, TNA’s brightest homegrown star, the longest reigning WWE Champion.
Of course, all this is predicated on Styles first retaining the title at SummerSlam. But while his opponent for that PPV is TBD and there’s certainly a chance he could lose, for the above reasons I believe he will retain at both SummerSlam and Hell in a Cell and go on to become the longest reigning WWE Champion of the modern era.
As for the other milestones – those are much less likely to happen.
As BITW44 also pointed out, there has not been a world title match at Survivor Series since 2015. Thankfully, I think there will be one this year – but I’m very hesitant to predict that Styles will retain. Furthermore, even if he does retain through Hell in a Cell, he might not be champion come Survivor Series: he could very well lose the title at the Super Show-Down in Australia in October.
However, even if Styles drops the title before Survivor Series, this is not his final run with the WWE Championship . If he doesn’t break those combined reign records this year, I won’t be surprised when he does in the future.