I'm just getting back into trading after a long layoff and I'm rusty. I was looking at conversions in SPY yesterday afternoon. As you can see in the IB snippet, conversions for Aug expiry were trading about $1.80 below spot at the 435 and 455 strikes, but only $0.65 below at the 475 strike. There aren't any concerns around hard to borrow, so that's not the issue. Maybe early expiry is a factor? I can't quite wrap my head around it. Any insight would be appreciated. Thanks!