India’s benchmark Sensex index of the Bombay Stock Exchange plunged Friday as global markets reacted to a sharp decline on Thursday in the US Dow Jones Industrial Average, which hit a low for 2008. Meanwhile, on Thursday, gold made its largest one-day gain in 23 years and oil reached a record $142 a barrel. Just how bad the markets have become for some icons was apparent in the performance of shares of General Motors Corp., one of the fading global corporate icons, which turns 100 years old this year. GM’s shares sank to a 53-year low in intra-day trading on Thursday in New York, where they fell to $11.21 a share. That was their lowest point since 1955, according to ‘Reuters’. Mint decided to look at what was happening back in 1955.