The FTSE 100 has had its strongest January for 24 years, with more than 6% of value added to Britain's top firms.
The UK's blue chip companies have grown £96bn in the first month of trading - climbing at more than £3bn per day on the index .
The growth of 6.4% is the best year start since 1989.
Equity trading reached the 6,000 mark on the first market day of 2013, and peaked above 6,300.
The last time the index had climbed so high was in 2008 before the collapse of Lehman Brothers.
The rally in markets has also been felt further abroad, with Tokyo's Nikkei index rising 7.2% and the Dow up 6% in the same period.
Last week the US also revealed that its economy had shrunk by 0.1% ahead of it resolving the so-called fiscal cliff.
The FTSE 100 climb in 2013 comes after the premier UK stock listing rose by 5.8% in 2012.
Equities have become an increasingly attractive investment option for people during the period of historic low interest rates.
Bonds had become a haven for cautious investors since the global financial crisis more than four years ago.
"Optimism about economic prospects, record levels of company profits and hopes that the eurozone crisis is past mean investors are feeling happier about taking a punt on shares, at the expense of currencies and bonds," Sky News Business Presenter Dharshini David said.
"But with almost £100bn added to the value of FTSE 100 in January alone, markets may have gone too far, too fast and there’s a risk that the thirst for equities may not last."