According to this infographic and report, angel investment groups included other non-angel group co-investors in deals than they excluded.
Of all the investments by angel groups in 2011 covered in the report, 33% of investments did not have co-investors while 67% of investments had co-investors outside the angel group.
Out of those co-investment deals, 75% of the time they included non-angel investors such as venture funds.report, angel investment groups included other non-angel group co-investors in deals than they excluded.