only sensible i have found till now is low interest rate.
Quality can retain high roe just like a bond. so that this bond gets priced higher vs govt bond. but even then i find excesses..
frankly its all boils down to performance chasing which is fair enough, but don’t blind yourself with random fundamental logic.
yes if high growth continues, stock may remain expensive, hdfc bk has grown 25%+ for all quarters. V rare. no quality cos has done that to remain expensive for sustained period