It depends what you mean with Wall street. 

By law public investment funds are not allowed to invest into cryptocurrency. This is because the fund needs a guarantee by the clearinghouse they can't lose their investments. That's why a cryptocurrency etf will be bullish, a lot of institutional money can't enter this sector at this point in time.  

People who work on wallstreet can however buy cryptocurrency privately, not as an institutional. There have been instances where this has been the case.  For example in April this year George Soros gave a member of his family office approval to trade cryptocurrencies.