Alter table shrink running for over 5 days

 Hi Gurus

I have nullified the blob fields in a 550 GB table. Only a portion of the data, close to half of the total number of rows has been nullified. Now I am running alter table enable row movement and alter table shrink space cascade. The shrink space statement is running for over five days. Do you think its a normal behaviour? Has anyone shrunk 550 GB table and knows the estimate of the time.

Thanks For the response.

KLA.