Jim Cramer's Stop Trading! Buy Dollar General

It's OK to buy Dollar General (DG Quote), but do it for the right reasons, Jim Cramer said Tuesday on CNBC's Stop Trading! segment.

Cramer noted that shares in the retailer were up 3.5% Tuesday afternoon on speculation that Bain Capital and other private equity investors are considering a bid. Cramer said he would buy the stock at a recent price of $16.50 -- but only because Bank of America recently put out a bullish research report on the company.

"Buy it on the basis of the research," Cramer said, adding that he believes Bank of America does the most rigorous retail industry research on Wall Street. He added that Dollar General and its dollar-store peers have been "radically out of favor," so it could easily go higher regardless of whether a bid actually materializes.

Cramer also says he would be "tempted" to buy Under Armour (UARM Quote) on Tuesday's 3.7% pullback, in spite of an underweight rating from Morgan Stanley. He said the apparel group had been stuck in a bear market for 20 years, so it doesn't make sense for Under Armour's run to have ended so soon.

"These stories tend to last longer," Cramer said. He said he sees "more momentum" in the stock, which last fetched $46.36.