After months of languishing on the bourses and recording new lows, the NSE PSU Bank index, has gained a little over 15 per cent since March, outperforming the benchmark Nifty (up 9.5 per cent). Analysts attribute much of the post-Budget rally in stocks of public sector banks (PSBs) to the government's capital infusion and consolidation plans. Also, that some part could be on account of bottom fishing. The recent formation of the Banks Board Bureau, meant to select heads of state-run banks, help improve their governance and develop innovative financial methods to raise capital and other measures, has added to the sentiment. Investors, however, need to be cautious. The fundamentals of PSBs haven’t changed meaningfully since the December ’15 quarter. Nor will merging these purely on the basis of size (bigger bank acquiring smaller peer) lead to significant gains. Take Punjab National Bank (PNB). In the December quarter (Q3) of 2015-16, it saw a 93 per cent slip in profit due t