  We introduce a new electronic aromaticity index, AV1245, consisting in the
average of the 4-center MCI values along the ring that keep a positional
relationship of 1,2,4,5. AV1245 measures the extent of transferability of the
delocalized electrons between bonds 1-2 and 4-5, which is expected to be large
in conjugated circuits and, therefore, in aromatic molecules. A new algorithm
for the calculation of MCI for large rings is also introduced and used to
produce the data for the calibration of the new aromaticity index. AV1245 does
not rely on reference values, does not suffer from large numerical precision
errors, and it does not present any limitation on the nature of atoms, the
molecular geometry or the level of calculation. It is a size-extensive measure
with a small computational cost that grows linearly with the number of ring
members. Therefore, it is specially suitable to study the aromaticity of large
molecular rings as those occurring in belt-shaped M\"obius structures or
porphyrins.
