shares of osb group fell 17 in early trade on friday after the company said late thursday that it expects to book an interest rate reversion adjustment of up to 180 million pounds 2294 million in its halfyear accounts shares at 0732 gmt were down 8020 pence at 39040 pence the specialist lending and retail savings group said that during the first half of the year precise mortgages owneroccupied and buytolet customers chose to refinance fixedterm interest rate deals earlier than previously expected as bank base rates rose osb said that it has reviewed customer behavior as they reach the end of their initial fixedrate period and now expects them to spend an average of fivemonths on new rates it therefore expects to book an effective interest rate adjustment of gbp160 million to gbp180 million on an underlying basis in the first half of 2023 the company also said that it expects to deliver 7 underlying net loan book growth this year while net interest margin for the first half is anticipated to be marginally ahead of expectations the company added that firsthalf administrative expenses are slightly below the boards views osb plans to report earnings for the half year ended june 30 on aug 10