The announcement was made last week of the IPO (initial public offering) with the intention of raising £20m.
Green told RangersTV: "It has been very encouraging and I'm now seeing the passion and commitment of the Rangers fans financially.
"We see it on the terraces, of course, but in these difficult financial times the response has been amazing.
"In the last figures I saw a couple of days ago over 8000 fans had registered – with some 20,000 fans on the website – and we have pledges of around £17m.
"And by the time we get to the cut-off date that figure will have risen.
"I would like to stress that any fan who backs up his or her pledge with a cheque will get their shares.
"I have had some calls from people concerned about that because we said the IPO would be up to £20m but fans will get their shares.
"It's much better than I expected. I don't think anyone could have predicted the response and it's testimony to what Rangers fans are about.
"They can see that the club is going in the right direction and this really is the icing on the cake.
"I don't think there is any doubt that we will now exceed all of our expectations."