NEW YORK (TheStreet) -- The S&P 500 climbed 1.2% and the Dow Jones Industrial Average jumped 1.5% Monday. Dan Nathan, co-founder and editor of riskreversal.com, said on CNBC's "Fast Money" the reason is simple: "window dressing" or buying stocks right before the end of the quarter likely added to the rally. 

However, he warned, in each of the last five quarters there have been pullbacks of roughly 4% in the first month of each new quarter. 

Karen Finerman, president of Metropolitan Capital Advisors, said the People's Bank of China considering some form of monetary stimulus was likely another reason for Monday's rally, and she expects to see slightly more upside Tuesday.

Volatility will likely remain in the market, said Guy Adami, managing director of stockmonster.com. As long as the iShares Russell 2000 ETF (IWM) - Get Report stays above $121, the rally is intact. If the iShares Transportation Average ETF (IYT) - Get Report breaks over $168, the broader market is likely to rally even further. 

It's interesting that stocks rallied on Monday despite the higher U.S. dollar, said Brian Kelly, founder of Brian Kelly Capital. He said U.S. earnings are likely to be disappointing because of the strong dollar, so many investors are concluding that a stronger dollar is bad for U.S. profits. 

Kelly remains cautious. With the CBOE Volatility Index I:VIX below $15, he recommended investors buy insurance on their portfolios, especially with the non-farm payrolls report coming out on Friday and earnings just around the corner. He's doing so with SPDR S&P 500 ETF (SPY) - Get Report put options.

GoPro (GPRO) - Get Report climbed 2%. Charlie Anderson, an analyst at Dougherty & Company, upgraded the stock to buy from neutral and assigned a $55 price target. GoPro's valuation has finally become more attractive, he said, trading at around 25 times his earnings estimates for 2016. He's not really worried about competition at this point and said future products could be in the pipeline. He also reasoned that the devices' average selling prices are strong. 

One reason Anderson may not be worried about competition is strong brand awareness, Kelly said. Consumers are looking for GoPro products, not knockoffs from competitors. 

Nathan, however, is "not a fan." Competition will hurt the company's market share and the valuation is not attractive. GoPro stock is likely headed down to the $30s, he said. 

The conversation turned to biotech, which saw a number of deals Monday. For investors without a lot of background in biotech, look at the exchange-traded funds including the iShares Nasdaq Biotech ETF (IBB) - Get Report, Kelly said. Many of the stocks are breaking out but the sector is volatile. Nathan said he'd avoid many of the small-cap biotech stocks that have little or no revenue. 

Adami pointed out companies such as Celgene (CELG) - Get Report, Amgen (AMGN) - Get Report and Gilead Sciences (GILD) - Get Report have "unbelievable" balance sheets, "great products" and are "extremely fairly valued." 

Kelly said Tesla Motors (TSLA) - Get Report CEO Elon Musk chose a good time to send a bullish tweet about a new product, with the stock hovering near support at $180. Kelly isn't a buyer, however.  

Using $177 as a low, investors can stay long Tesla Motors, Adami said, as he chose the stock for his final trade. Nathan said to sell Intel (INTC) - Get Report, Kelly is buying SPDR S&P 500 put options and FInerman is a buyer of Citigroup (C) - Get Report. 

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