Hi, guys I asked this question in Software but I think that might be the wrong forum; no takers. Hopefully this is the right forum. I'm trying to calculate an equity column for an automated trading system in a spreadsheet. Column G is the adjusted close (yahoo eod data), column K is my security position (+1 if I'm long, -1 if I'm short and 0 if I'm out) and column P is my equity. Row 99 is the day before row 100. My equity cell formula is P100 = @IF(P99<0, 0, P99*@IF(K99>-1, (G100/G99)^K99, 2-G100/G99)) I think the short-sell formula is wrong. Any ideas how I can correctly program the equity cell for a short-sell? I can almost see it, but not quite. Thanks in advance.

Hi, OddTrader I think you're referring to an error message? If so, that's not the problem. The formula "works" great, I just think it's a garbage output. Short-selling is the opposite of buying long in more ways than one. With buying long, you have a finite downside and a potentially infinite upside. With selling short, you have a finite upside and a potentially infinite downside. It occurs to me that the formula I posted has a potentially infinite upside, and that's gotta be wrong. Thanks for your input all the same.

Because I'm looking at going short as well as going long, it's possible to hit that "infinite downside" and get more than wiped out. So "(P99<0," is there in case that happened in a previous cell: I just replace any negative equity with zero all the rest of the way. (G100/G99)^K99 is my change in equity when I'm long (K99=1) or out (K99=0). It seems to work OK for those two cases. I think I see the short-side problem. I have to refer all the way back to the entry price, not merely the previous price in the trade. Gotta figure out some fancy addressing here. :eek:

Perhaps simply try "ChangeEquityDaily": (PriceEODToday-PriceEODYesterday)*Sign(LongShortQtyEODYesterday)*Abs(LongShortQtyEODYesterday)

:eek: P100 = @IF(P99<0,0, Q99*(1 + K99*(G100-R99)/R99)); Q99 = @IF(K99=K98, Q98, P99); R99 = @IF(K99=K98, R98, G99). Thanks, OddTrader!