As Stocks Rally, Market Flooded With New Shares

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The strong stock market rally this year is being met with a heightened level of supply, setting up a big bet that retail investors will keep buying what Wall Street is selling.

In the past, that's been a risky wager, with too much supply depressing market prices.

But with the market on its longest streak in more than six years without at least a 5 percent pullback, suppliers are figuring there are many more willing to step in.

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New offerings jumped to $13.6 billion last week, the highest of the year and more than five times the previous week's $2.5 billion, according to market research firm TrimTabs.

Total float in the market—or the amount of shares available for purchase—has increased 1.4 percent this year, even though corporate buying has approached five-year highs.

"As long as underwriters are dumping $10 billion per week into this market, it could be tough for stock prices to move much higher," TrimTabs said in an analysis.

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The surge comes as bullishness in the Investors Intelligence survey of newsletter authors hit a three-month high and Wall Street analysts remain largely positive on stocks.

However, warnings are intensifying that the market could be in for the near-term pullback it has avoided all year.

Standard & Poor's Capital IQ has asserted the market is in for "a major pullback" between 8 percent and 10 percent that will play out over two to three months.

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"In our view, upside is limited and we would continue to sell into strength," Mark Arbeter, S&P's chief equity strategist, said in a note to clients.

S&P Capital IQ's long-term outlook remains positive, though its 12-month S&P 500 target of 1,670 is only about 2.5 percent from the current level.

TrimTabs also is bullish, while remaining skeptical of the market's underpinnings.

"We are under no illusions about what is driving this rally," CEO David Santschi said. "Stock prices are moving higher almost entirely due to central bank liquidity, not corporate or economic fundamentals."

_ By's Jeff Cox. Follow him on Twitter @JeffCoxCNBCcom