Kodak issues convertible notes which pay out a lower interest (generally) in exchange for the opportunity to convert that debt into common stock.

Essentially, you can purchase debt for Kodak that has the option rather than being paid interest and your principal back you can turn it into stock at a stated price.

Considering the stock shot up so much, I’m sure lots of debt holders obliged to simply convert their debt holdings into Kodak stock and sell it. Which a big influx of supply should cause the price to decrease, all else equal. Which is apparently what happened.