IGIndex is just as bad for slippage. A friend got slipped 100 ticks on gold the other day.
Funny how they always promote instant execution, no requotes, yada yada. But as most SB brokers, they make money by trading against the client. So they got to do something to take your funds and that is in the form of slippage.
Yes, I don't remember ever having positive slippage from IG, but always the worst negative slippage, for any excuse.
I've posted this elsewhere, and I am certainly not in the habit of defending bucket shops. But honesty compels me to say that I never had a problem with IG when I used them.
To give context, this was purely on their version of ES, NQ and YM futures. I always checked every trade against the real market, and the prices were pretty much spot on (small differences of course - there are no 0.1 pt increments in ES obviously). In addition, I didn't see suspicious spikes - for example, the low of a bar taken out on IG's charts where it wasn't on the real charts.
I also kept a note of slippage, in and out. It was rare, and it went both ways - slightly more often in their favour than mine, but as I say it was rare in any case.
I also had many occasions where price came within a tick of my stop but didn't hit it. In all, I really can't point to examples of shenanigans. I stress again I'm talking about index futures only, I can't speak for cash indices or spot forex (which is like the Wild West in any case).
I liked everything about the platform really, and only changed for two reasons. One, I couldn't consider doing this professionally if there was the possibility of a conflict of interest, no matter what. I want the broker to make money off me in a clear and transparent way, though commissions alone. That aligns our interests.
Second, costs for futures. YM cost me 4 ticks in spread with IG, which is the equivalent of 20 bucks per contract. A futures broker should be under 10 bucks ($5 for the 1 tick spread and less than $5 in commission). Even FP with increased commissions is only $12.50 (1 tick plus $7.50 commission).
ES is a 2 tick spread - $25. With a broker that should be under $17.50 ($12.50 1 tick spread, under $5 for commissions), and with FP it's $20.
Trading even say just 5 YM contracts, that's $37.50 per trade. On average I might make 15 trades a month, that's over 500 bucks a month better off.
So cost-wise it started to make no sense, even leaving aside the fact that IG is on the other side of your ticket.
But like I say, just to be fair (and just in my experience) I didn't see any cheating going on.