According to a new 9to5Mac report, citing unidentified sources, an additional version of the fourth-generation iPad with Retina display - featuring a massive 128GB storage capacity - is currently being developed by Apple.

With the existing fourth-generation iPad with Retina display models available in three storage options: 16GB, 32GB, and 64GB, the report chiefly implies that the new iPad 4 model being readied for launch by Apple will essentially boast a notably enhanced storage capacity.

As per the 9to5Mac sources, except for the notably beefier storage, the new version of iPad 4 will merely expand the current line-up of the tablet, without any change in design. The color options and the wireless combinations for the new iPad model will also be the same as the ones available for the existing three models of the Retina display-equipped tablet.

Despite the fact that the report stopped short of disclosing the expected price of the reported 128GB iPad 4 model, it did mention that the new model is being describes as a "premium SKU" - stock keeping unity - which will join the present iPad 4 lineup.

Moreover, going by the information shared by one of the sources - an insider at a bigwig US retailer -, the 128GB iPad 4 model has the `Ultimate' identifier, which is befitting for the unit; given the `Good' identifier of the 16 GB model, and the `Better' and `Best' identifiers for the 32GB and 64GB models respectively.