buyback of shares

sbhaktha (bcom + lawstudent @ present)   (109 Points)

30 March 2019  
A Ltd. had entered into an Agreement with B Ltd where by B Ltd. had subscribed 500000 worth shares and after five years A Ltd. was to refund the amount at 18% IRR. now A Ltd has repaid the amount and B Ltd. has returned the share certificate. whether this amounts to buy back?