The change is partly the result of the strengthening share prices of the almost 30 listed Tata companies.

BBC: India: Tata becomes India's wealthiest group

You see, I expect the prices of my shares to fluctuate in value throughout my ownership period, which in most cases is several years, and so I only consider selling my shares if there is a fundamental negative change in the company's prospects or share prices become irrationally overvalued.

FORBES: Magazine Article

But there has been so little volatility in share prices in the past two years that any sharp change is unsettling.

ECONOMIST: Collywobbles

The appetite of investors for risk may change in predictable ways in response to particular changes in share prices.

ECONOMIST: Heads, shoulders and broadening bottoms | The

First, it would change the widespread market perception that the Fed responds to asset prices asymmetrically, cutting interest rates if share prices fall sharply but never raising them when share prices climb.

ECONOMIST: Central banks, all a-quiver | The