Delivery failures.....what has happened is that purchasors (or purchasor it its just one individual) of RVX.WT have not had the shares (warrants in this case) purchased delivered into their accounts.

Right now let's say I put in a buy for 1,000 RVX.WT warrants at market...the order gets filled.  Now the party (or parties if it was more than one) have 2 days to deliver what I paid them for...if they don't, then its a delivery failure and the TMX has what's called a "Buy-In" facility to locate the shares....Its explained here:

https://www.tmxmoney.com/en/research/buy_ins.html