Portfolio manager isn't convinced of the current rally's staying power. But he's sticking to his guns.

Roger Nusbaum says he isn’t convinced that the current three-month-old stock rally is more than a brief respite from a longer-term secular bear market.

But that isn’t stopping the portfolio manager at Phoenix-based Your Source Financial from seizing opportunities when they present themselves. Nusbaum last week increased his clients’ exposure to the iShares Dow Jones U.S. Technology ETF (NYSE: IYW).

His client portfolios still generally have around 20% in cash. At one point last fall, that was up to 25% in cash. It was the largest amount on a percentage basis that Nusbaum has ever held out of circulation, he says.

“I’m skeptical for a whole host of reasons that a new cyclical bull market has started,” said Nusbaum. “The extent to which the Fed and Treasury have printed money, issued debt and are monetizing some of that

We’ve been so caught up watching stocks soar we haven’t paid much attention to one of our favorite asset classes: commodities. Yesterday, we mentioned we were bullish on agriculture. In particular, we like the PowerShares DB Agriculture ETF (NYSE:DBA). Underground investor Jim Rogers is also bullish on agriculture. He says Asian demand and low inventories will lead to a long secular bull market in corn, soybeans and fertilizer. As Brian Hunt wrote in yesterday’s DailyWealth, DBA “is one of the largest and most liquid ways to trade agriculture through the stock market. It divides its holdings evenly between corn, soybeans, wheat, and sugar.”

From this chart, you can see that DBA is has been showing some strongly bullish action lately. And it has the Jim Rogers seal of approval.