How will my supervisors track my performance?

I work for a bank as a middle level manager. However, in the last two months I have had more than five managers, three of which have been serving in acting capacity. In such circumstances how does the company track the performance of workers if managers only stay around for a few months before they leave? Arnold

What you are describing are serious challenges of gate-keeping, resourcing, leadership development and succession planning.
The people your bank has been appointing in rapid succession as your bosses have, in the company’s estimation, failed to measure up to standard yet this is clearly a result of the bank’s failure to prepare and develop them to take up leadership positions when they fall vacant.
The sudden departure of key talent then leads to panicky appointments of ill-prepared people for the vacant senior roles and, end setting them up for failure when they realise too late that the appointees were not suited for the new leadership challenges.
The problem of such panicky moves is that people’s careers get adversely affected when they are sacked for incompetence for no cause of their doing.
In addition, it’s a big loss to the bank in terms of resourcing costs and learning-lead time.

Leadership skills have to be deliberately imparted and developed in people, for example, you can employ a brilliant journalist but that does not mean he or she will automatically turn out to be a good editor when charged with the responsibility to lead fellow journalists.
He or she has to be nurtured or developed with a target to turn him or her into a leader who will readily offer better than others. This takes time, serious investment and targeted movements.