I study US commercial banks data. I look at the notional amounts of their different OTC interest rate derivatives for the recent years. When I look at non-dealer banks (i.e. end-users), I find that they have a relatively high share of written interest rate options (in terms of the notional amount of the total portfolio of interest rate derivatives). The share of written options is comparable to share of forwards, and much higher than the share of purchased options (but lower than the swap share which is the most used instrument)
I would like to understand why the share of written options for non-dealer banks is relatively high compared to the share of purchased options or other instruments? Is it a specific hedging strategy? Note that the written and purchased option variables also include caps, floors, collars, corridors and swaptions.