Help explaining a recent trade

[RS5]

Can anyone shed light on what has occurred with this trade?  I had placed a stop order to BUY 1500 @ $88.20 for market open today (Image 1).  

Previous Close was $88.09.

Order gets filled at opening @ $89.54 (!!!) then is stopped out at my original stop level @ $88.02 (Image 2).

Resulting in the following chart (Image 3).  

Am I looking at some sort of grotesque slippage? 

 

 

 

[dmedin]

What's the slippage factor on that instrument?  Doesn't the likelihood of slippage increase during such parabolic moves?

[RS5]

I should add that the trade is for US shares ticker code PMTC and the candles are 15 minutes. 

[Guest JT8888]

Buy stop order is to buy as soon as $88.20 triggered even if this is a worse price, hence you got a fill.

You wanted a limit buy instead.