Greek politics has become extreme and fractious, MacKinnon said, and it is not clear whether a new administration in Greece could implement the wishes of its lenders, the EU and the International Monetary Fund.
With most of the vote counted, official results showed New Democracy would win 30 percent of the vote and 130 of the 300 seats in Parliament. Syriza had 27 percent and 71 seats, and the pro-bailout PASOK party had 13 percent and 33 seats.
"Basically, all this does is keep the patient on life support, but doesn't resolve the basic problem," he said. "So whatever the reaction in the stock market in the next couple of days, I would say treat with caution."
One market strategist, Paul Christopher of Wells Fargo Advisors, said last week that a Syriza victory could have led to a 15 percent decline in the Standard & Poor's 500 index within weeks.
That is because no one is sure how bad a Greek exit from the euro would be. Greece would almost certainly default on its debt, triggering losses for European banks that own its government bonds.
The worst case envisions a worldwide lending freeze similar to what happened after the investment bank Lehman Brothers went under in September 2008, during the U.S. financial crisis.
That threat has been dodged at least for now. But another investment bank, RBC Capital Markets, warned its clients on Sunday afternoon that Europe still lacks a "grand solution" for its debt crisis, and that "domestic fixes will always disappoint."
Even if Europe finds an answer, investors have to contend with other big problems in the world economy. Job growth in the United States is slowing, and China's white-hot economic growth is cooling.
Central banks of countries around the world have signaled they are ready to step in if the international financial system comes under severe stress or if the world economy gets much worse.
That prospect was enough to trigger a 270-point rally in the Dow on Thursday and Friday. But the sentiment of stock analysts heading coming out of the weekend was still decidedly negative.
"I think investors can only end up being disappointed," MacKinnon said.
Joshua Freed reported from Minneapolis. AP Business Writer Christina Rexrode contributed to this report.
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