Fundamentally if you look at the shorting of SYR(and others) it...

Fundamentally if you look at the shorting of SYR(and others) it is the exact reason why it shouldn't be allowed and they cant loose.
most institutional substantial holders have multiple branches that hold the shares (have a look at the last couple of substantial holder anns and you will see this)

so a fake example for my point
inst X holds say 10% or registry split into 2 groups of 5% each (a and b to make the maths easy 20M shares each)
if times are good SP goes up they both make money (how retail needs it to work)
on negative news or poor outlook (like we have now)
a lends to b and b lends to a. they start shorting on large volume adding to SP decline, panic selling starts which crashes SP and it goes from $1 to 50c
at this point news stabilises and both parties cross trade back there borrowed shares(after market) and make 50% profit on the short each

they are now (on paper) in the same financial position as if the sp was still $1 (due to short gains) and we are all down 50%, the point that the original SP ave was $1 is negated

this may not be 100% correct and very generalised example but it is how I see it working within SYR for the large part from the anns and who is borrowing / returning.