Hi Viking,
To buy controlling stake in IDBI, you would need close to US $2.8B . FIH would likely be a part of consortium as has been indicated here . FIH can also contemplate selling stake in NSE which can easily fetch them 200M+
My understanding regarding IDBI is that there is a ton of value that can be potentially unlocked by having a credible promoter. IDBI is a whale and merger with CSB would definitely give them scale needed to retain a talent like pralay mondal. CSB has already hired some people (CXO) from IDBI in the past 12 months so this has been on cards for a while. The depressed valuations of CSB indicates the same.
I would rather FIH not touch IDBI but Prem probably will not be able to resist since this is a once in a lifetime opportunity to build a top 5 bank in India. As long as FIH does not touch its BIAL stake I am fine with it . Given the incredible aviation growth in India I would be surprised if BIAL is not worth more than $5B whenever it IPOs in the next 12 months. Next year is the election year in India so FIH might try to push the IPO through before that if markets are favorable.