I use an online tool that lets me enter stocks in lots, but it's not clear how to track when some of lot is sold?

Does one just subtract shares out of the lots until they reach 0?

  • Pros: Easier to track shares per lot
  • Cons: Total % gain/loss of equity is lost. Eventually all lots go to 0.

The only other option is to create a lot with negative shares. What is the standard method?

  • Pro: Lot information remains after shares are sold
  • Pro: Potentially can keep track of average performance of all lots
  • Con: Harder to match shares with buy/sell lots
  • Con: Potentially breaks some calculations?

There are a number of metrics that you can track and the ease of doing so depends on the whether you are designating your closing trades or not.

If you are not designating which shares you are selling (or buying if short), tracking total open cost basis is easy. Purchases are debits and sales are credits. You maintain a running total cost summary (dollars at risk). Dividing that by the number of open shares determines your average cost per share for open positions.

It's a bit more complicated if you are designating which positions are sold. You do the same as above but you have to remove part or all of specific security purchases.

For decades I have done this myself. The core is a pair of 'master' spreadsheets. The first lists the transactions sequentially and the second is closed positions are segregated for tax purposes.

If needed, I use a third spreadsheet for any single underlying that breaks down the P&L of each of the remaining purchases that are open and if options are involved, it tracks them as well. This sounds a lot more daunting then it really is since once you have a functional spreadsheet, it can be copied and used for any security.

On occasion, I have used a professional tax program which handles the tax side of it accurately and completely. It does some positional analysis. But that need has only been for years with heavy trading (like 2008).

I don't know what, if anything is available online that is free and does this. There should be something that manages non designation of shares but I would surmise that there's not going to be much, if anything, available for tracking designated sales.

  • Yes, I'm designating the shares from individual lots. However, my broker is tracking most of this info. The online tracking is mostly for my personal convenience, but I'ld like it match as close to actual accounting as possible. So does it makes sense to create a lot with negative shares? – cmcginty Feb 16 '19 at 5:49
  • The main reason that I do all of this heavy lifting is that I need to know what my cost basis of each purchase of a position is. The 2nd is that brokers don't always get EOY numbers right. It's no problem if you own some number of round lots of XYZ but it's not the case when you have incremental odd lot buys and sells along the way. If the broker provides you with what you need, no problem. Otherwise, DIY. If using a program that accepts creating an odd lot with negative shares and it does the math correctly, it makes sense. If not, not so much. – Bob Baerker Feb 16 '19 at 14:19

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