Despite their caution about the deal, which has staved off spending cuts for two months and halted a number of tax hikes, markets have rallied.
At the time of writing the FTSE 100 is up 2.28 per cent and above the significant 6,000 figure for the first time since July 2011. US and European markets have also surged.
However, the vast majority of industry experts believe the rally is likely to be short-lived as the current deal is just another example of politicians kicking the proverbial can down the road.
Mike Turner, head of global strategy and asset allocation at Aberdeen
"The tax rises agreed by the House of Representatives may have averted a near-term recession, but an economic crisis induced by the deteriorating credit worthiness of the US still looms." "The US deficit remains too high and despite the interest charged being extremely low, action needs to be taken to address the unsustainable growth in federal debt."
"Spending cuts are required but need to be balanced with incentives encouraging companies to invest some of the huge sums of cash on their balance sheets. In its simplest form this means certainty over the longer-term fiscal and growth outlook."
"Until a long-term plan is agreed which reduces the annual budget deficit to less than 3 per cent of GDP, investors are likely to remain nervous."
Richard Lewis, head of global equities at Fidelity
"US politicians have reached a compromise on extending the Bush-era tax cuts.""Democrats wanted to enshrine these cuts for 98 per cent of the population, the Republicans argued for 100 per cent, and they have settled at 99 per cent. After all the drama, that is the extent of the compromise: deeply unimpressive."
"The issues of the debt ceiling and spending cuts have been left for another day, actually just a few weeks away, when all this partisanship will make headlines once again."
"There is no financial market pressure on politicians to do any better due to the continued unprecedented easing from the US Federal Reserve, which just before Christmas announced a rise in their scheduled rate of asset purchases from $40bn per month to $85bn per month until further notice."
"So US asset prices rally on the easy fiscal and easy monetary-policy mix. We are unlikely to see much change in behaviour unless or until serious US dollar weakness calls time on the Washington shenanigans."
Tim Cockerill, head of collectives research at Rowan Dartington
"The Democrats and Republicans have for the moment come to a compromise on tax rises and spending cuts to address the fiscal cliff.""Whilst they both wanted their own way, neither wanted to be responsible for pushing the US economy back into recession."
"For now it’s the Democrats who have come out on top, having got more of their demands through than the Republicans. However, in many respects, all they seem to have done is kicked the can down the road on spending cuts for a couple of months."
"Very shortly both parties will have to negotiate the debt ceiling and spending cuts again and, of course, the impact of their agreements won’t be known for probably six months."
"Will they have got the mix of spending cuts and tax rises just right, or will they have over- or under-cooked it?"
"The outcome of these negotiations is very important because the right mix will give businesses the confidence to start investing and hiring, and could kick-start M&A activity. If the mix is wrong, companies will keep sitting on their piles of cash."
"So logic says that they are likely to agree a sensible compromise, but that has not been achieved yet."
Thomas Becket, chief investment officer at Psigma
"If there was ever a pyrrhic victory in modern-day politics it was this, although the president will doubtless claim victory, as there were tax-rises forced upon the wealthiest." "On a more positive note we believe that the expansion will strengthen later in the year as the housing market continues to rebound. The package will reduce growth, but not eliminate it and once the dust has settled after this miserable episode, we hope that confidence and, by implication, growth, can improve."
"There will be many who want to take the positives from this last-minute deal and expectations were set pretty low over the last week or so, so there is certainly scope for markets to rise higher in the coming sessions, as we have seen in Asia and European and US futures this morning."
"Indeed, despite the politicians’ best efforts, we have not altered our view that 2013 has the potential to be a decent year for equities. However, the scars will run deep and the rabid atmosphere amongst the US politicians has just got more poisonous."
"The biggest risk to markets in 2013 is the politicians and sadly the end of 2012 does not augur well."