Wien said that he thinks the economy "needs" a continuation of easy monetary policy, because there is no fiscal stimulus helping to bolster activity. "We're totally dependent on monetary stimulus to keep this economy humming along at a modest 2 percent growth rate," he added.
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Wien also thinks there is room for increased government spending, and said that it is precisely what the economy needs.
Comparing the U.S. government budget deficit to GDP in 2010 and 2013, Wien said that the U.S. government "could spend some money," focusing on job training, infrastructure, research and development—investments he believes hold the potential for future growth.
"The fiscal side would help the 80 percent" who aren't benefiting from the stock market gains and "the rise in high-end real estate prices," he said. The key is to stimulate the U.S. middle class, the middle 60 percent of Americans, "and we've got to provide incentives for them to" spend.
Wien said that despite unprecedented monetary easing, economic growth has continued to disappoint and this slack in consumer spending will be felt in the broader economy through the end of the year.
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"There just isn't enough demand to absorb the amount of manufactured products that are being produced everywhere," he said, explaining his view that investors should be worried about the second half of 2013. He also expects that the S&P 500 will likely be flat by the end of the year, "but we'll probably go lower first."
Wien explained that after disappointing GDP numbers in the first half of the year as well as a host of disappointing earnings and revenue numbers from individual companies, "that usually means that more earnings trouble is ahead." Wien said that disappointing revenues is what he's "most worried" about and the market rally this year is likely to cool off in the second half.
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Wien said that he's "not recommending any purchases of Treasurys," instead he recommends focusing on individual companies in the pharmaceutical and technology sectors as well as Mexico and Japan.
"There are plenty of places to go," he said.