the norm (and fairest imo) is to allocate rights issues based on...

the norm (and fairest imo) is to allocate rights issues based on how many shares you held previously. if you held 1% of the company and they do a rights issue for 100m shares, you're can take up 1m. if you held 0.1% then you can get up to 100k etc. then whatever isn't taken up from that gets allocated pro rata again based on your pre-existing shares. for a regular placement then sure you run it as first in first serve, but point of a rights issue is to allow existing investors to retain (at least in part) their existing ownership of the company.