What is the meaning of "Proceeds of Disposition" on Form T5008?

Yes. Proceeds related to short sales of securities are reported on a trade-date basis in the current year the trade is executed and not the year the sale is covered. Short sales of options are not reported. Rules that apply to short sales are complex. Refer to…

As proceeds are reported on a trade date basis a sale is reportable in the year it is executed not settled. In the case of bond sales which take place in December but which do not settle until the following year, the sale proceeds will be reported in the year of the trade, and accrued interest, if any, will be reported included in the following year’s 1099-INT, when the funds are received in your account…

Form 1099-B Proceeds Form Broker and Barter Exchange Transactions reports proceeds from securities transactions including sales of stocks, bonds, short sales, redemptions, tenders and bond maturities. Additionally, profit and loss from futures is also reported on Form 1099-B…

Commissions and exchange fees are included on box 21 of your T5008 form. Other fees such as interest, monthly activity or market data fees are not included…