"I think the [U.S.] market has got a number of challenges – one, it is very high in value and If we get better data, Fed worries come straight back after a few days and bond yields go up and equity markets have got to compete with that," O'Neill told CNBC.
"If we going to have a global bull market this year – it will be led by something other than the U.S. That is possible, but I am not so sure about the U.S. sustaining leadership," he said.
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Investors instead should look to emerging markets, he said, and Germany, which is "trying to give a bit more leadership to the mess known as Europe".
U.S. stocks failed to end higher in volatile trading on Thursday, snapping a four-day winning streak, ahead of the widely-watched government jobs report. The Dow and S&P 500 hit record intraday highs earlier in the session.
O'Neill pointed to non-farm payrolls expected on Friday, as poor weather has muddied the data so far this year and investors may now be in for a shock.
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"I think the whole consensus is that it was just the weather and we are going to rebound. We are coming into the data now that should reflect that – so if we don't, people are going to be a bit surprised. Today is going to be a big day for U.S. data," he said.
India and Russia
O'Neill dismissed claims that the 'R' or Russia should be dropped from the BRIC acronym in light of the recent annexation of Crimea. That move led to a 15 percent plunge in Russia's MICEX index from the start of the year to mid-March. Russian stocks have since recovered some ground and year-to-date are now down over 6 percent.