Exercising or trading warrants are not an issue. In the example you gave with the A warrants if they are not trading at $4.60 or less of the share price simply sell that many shares and exercise the warrants to cover that short term short position. Your brokerage will be more than happy to accommodate your request as there is zero risk for them. The only challenge that you may run across is in a registered account, RSP or TSFA in Canada. Brokerages and trustees don't like to go over a month end in a negative position. Plan your transaction so that it can be settled prior to a month end. All of the last issue was only done in accounts that were settled through CDS so the exercise of the warrants and issue of new shares should be done exceptionally efficiently.

tada