Exactly. Like many things it is simply driven by supply and demand. Currently there is low supply of shares available for them to borrow, so the borrowing rate increases. Just a week or two ago the rates were below 50%.

Note that I've never personally shorted a stock or borrowed shares, but I've been monitoring iborrowdesk since the February short attack. The rates posted there seem to clearly correlate with shares available and I could see another short attack brewing. Based on what I've seen, they are not done and many appear to still be holding their short position.....I'll be curious to see what OTC markets shows when it updates to reflect 5/1/20 short interest....4/15/20 shows 8.1M shares). The pressure is building and I've never seen the rates of CYDY over 100% since I've been monitoring....(they were I believe 99% back at the peak in February shortly after the Culper and short attacks).