I'm still a bit unclear about how my prior costs get split (spreading the cost basis over all shares owned post-split vs artificially cutting the price of the pre-split shares in half); here is an example, looking at it another way...

If I buy 100 shares of ABCCorp. for $30 per share, the cost basis is $30 x 100 shares or $3000 (plus any commission, but I'll skip that here).

After my purchase, they have a stock split of one "new" share for each "old" share - a "2-for-1" stock split. I get 100 "new" shares and now have 200 shares.

If I decide to sell, the total basis in the "old" shares was $3,000. Now that I have 200 shares, don't I spread the cost basis over all of my shares? (My new "per-share" cost basis would be $3,000 divided by 200 shares, or $15 per share.

Is that how it works? I don't actually go back and reduce the cost of only the first 100 shares by 2 (to $15)... rather it comes out in the calculation over all the shares owned post-split, right?

Thanks again,
Mike