Stock bull Bill Miller cites two factors that could derail the 8-year market run

Bill Miller: Value shifts to these controversial stocks

Making money in the stock market is "more about time than timing," value investor Bill Miller told CNBC on Thursday, advocating investing for the long haul instead of trying to time the market's near-term moves.

The bull market in stocks, which began in March 2009, will continue until equities become more expensive than alternatives or if the economy goes into recession, Miller said on "Squawk Box."

Neither is happening right now, because the economy continues to recover since the 2008 financial crisis and stocks are not expensive relative to low-yielding bonds, he reassured.

"The [stock] market is not terribly expensive, and the market has a tailwind," he said. "As long as the economy is growing and earnings are growing, the market is well underpinned."

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Stock prices would indeed be high now on a historical basis if the 10-year Treasury yield were trading around 6 percent, Miller said. But with the 10-year yield currently under 2.5 percent, the stock market should continue to do well, he added.

The Dow Jones industrial average hit all-time highs last week, eclipsing the 20,000 level. While it's backed off a bit since then, the Dow has gained up 8.5 percent since Election Day.

"The great 35-year bond bull market ended this summer," reiterated Miller, founder, chairman and CIO of Baltimore-based LMM. "We're looking for a long bear market. It's going to be a benign bear market, I believe, but still it's a bear market."

The political landscape surrounding President Donald Trump is the wildcard, he said, reserving judgment about pro-growth promises of better trade deals and tax cuts.

Miller said he was fully invested in the stock market before the election and remains so.

If the Federal Reserve, as projected, moves rates higher only gradually, that would be another check in the plus column for stocks, he said. "As long as the Fed's not hostile, it's good for the stock market."

The Fed held rates steady on Wednesday, at the conclusion its first meeting of the year.

When central bankers increased the cost of borrowing money in December, for the second time in a decade, they indicated three more rates hikes for 2017 were likely.

Miller's LMM, a partially owned subsidiary of Legg Mason, has $2 billion in assets under management. Miller is also portfolio manager of the top-performing Legg Mason Opportunity Trust fund.