Investors had been pinning their hopes on Barack Obama’s inauguration as the 44th US president to boost shares, but on the day the market disappointed.

The Dow Jones Industrial Average had its worst one-day drop since December 1, sliding 332 points to 7,949. It was the index’s first fall below 8,000 since November and the worst inauguration day in US history for stock prices, according to Bloomberg figures and the Stock Trader’s Almanac.

Mark Dampier at adviser Hargreaves Lansdown said: “I think there is a danger people are being over-optimistic about what Obama can achieve. The fanfare surrounding his inauguration reminds me of the excitement when Blair came to power, but look at what Labour has done to the economy here. There is always a big difference between what politicians promise and what they deliver.”

However, Dampier is something of a lone voice among investment experts who believe Obama’s election is a turning point for America.

More than a quarter of the fund managers questioned in the Association of Investment Companies poll of predictions for this year tipped the US to be the best-performing region of 2009, with some forecasting a 20% market bounce.

Tom Elliott at JP Morgan Asset Management said: “The new president will inherit some tough challenges, but a change in leadership may be just the catalyst the market needs, particularly if leading economic indicators begin to bottom out during the spring.”

Shares did rise briefly during Obama’s speech, but soon slid again as fears about the banking crisis mounted. The bulls claim Obama cannot be blamed for the fall, which was prompted by worrying disclosures from big financial names such as State Street, and expect him to tackle the problems head on.

In investment terms, much has been made of Obama’s $850 billion stimulus plan, a package of tax cuts and public spending designed to kick-start growth. Obama has said the plan will help to save or create 4m jobs.

Andrew Fisher at adviser Towry Law said: “I am hopeful the new president’s plan will encourage banks to open their purse strings and kick-start the US economy — and funds — back into ruder health.”

Not everyone believes it will be enough to pull the economy out of the doldrums, though. Cormac Weldon at Threadneedle, the fund manager, said: “Many of the stimulus-package measures are aimed at seeking to avoid the spectre of rapidly rising unemployment, as they are targeted at creating new jobs. Nonetheless, we expect to see unemployment rise over the next few months from its current level of 7.2%.”

Opinion is also split about Obama’s team. Dampier said: “One concern is that the Treasury team Obama has appointed has a lot of similarities with the Clinton administration. And these are the people who got us into this mess by getting rid of the amendment preventing deposit banks from acting like investment banks. It does not fill me with confidence.”

For investors, of course, the main concern is how Obama will affect the stock market.

The US equity market has historically generated strong returns after downturns — the S&P 500 returned 83% from 2003 to 2007 following a 38% decline between 2000 and 2002 after the bursting of the dotcom bubble. Prior to that, after falling 65% from 1929 to 1932 due to the Depression, the S&P 500 returned 190% between 1933 and 1936, according to JP Morgan.

Statistically, though, the first year of a presidency is not always a good time for the US market. In the 12 months after George Bush was elected in 2000, for example, the US market fell 8.1%, according to Standard & Poor’s.

That said, markets often recover ahead of economies, and there is little doubt US shares look cheap. Research from Barclays Wealth indicates growth in US equity prices of more than 15% in 2009 and a further 9.3% in 2010, on expectations of a recovery in the second half of this year.

Russell Cleveland at Renaissance US Growth Investment Trust said: “While the US is not out of the woods, 2009 could be much better.”

Sectors that should do well under Obama include infrastructure and healthcare. Shares in US biotech company Geron, for example, soared 10% when Obama was elected due to hopes he will ease stem-cell research restrictions.

Funds such as Jupiter Ecology should also benefit from the new president’s enthusiasm for green energy.

For those seeking more general exposure to the US market, experts recommend funds including Martin Currie North America and Neptune US Opportunities.

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