I'm using the RTD function to do complex calculations on stock/bond prices in Excel, but I'm having trouble trying to write a formula or macro that will record the high/low prices during the day.

Since this is RTD, and the prices are constantly changing, I can't use the MAX formula. Basically what I need to be able to do is have a formula that any time the RTD price is greater than the previous high that it will update the previous high - as an absolute value, and not a formula.

I'd rather not use a macro, since I'll have a lot of these kind of commands running simultaneously, and macros would probably be too memory-intensive. But I'm willing to consider it, if that's the only option. In which case, is there a way for me to activate a macro from an IF command? (IOW, something along the lines of: =IF(A1>B1,--- run macro----,----do nothing---))