Subject: Re: brk, option expiration Friday,
I doubt they can take the stock to 505 today

The way I understand it is that there is no mythical "they" out there. But there are option market makers, and they like to stay delta neutral, and that means that depending on how many of each option is outstanding near expiry, they either have to buy stock or sell stock to get as close to delta neutral as possible. I think that's what those "max pain" calculators use as their basis, but I'm not 100% sure.