NEW YORK (TheStreet) -- There hasn't been a lack of volatility so far in the start to 2015, as the S&P 500 is down more than 1.25% on Tuesday, led lower by crude oil, which is down another 4% to $48 per barrel. On days where oil falls this much, investors are best off stepping to the sideline, Pete Najarian, co-founder of and, said on CNBC's "Fast Money Halftime" show. Even stocks that are unrelated to the selloff are getting hit, creating buying opportunities. 

However, those buying opportunities will likely get even better heading into the end of the week, according to Jon Najarian, co-founder of and Look at Apple (AAPL) - Get Report , he pointed out. The stock is down 6.5% in less than a week, but could go even lower in the next few days, as the first week of a new year tends to bring a lot of volatility as investors look to adjust their portfolios for the new year. 

The S&P 500 has broken below its 50-day and 100-day moving averages, said Steve Grasso, director of institutional sales at Stuart Frankel. If the 150-day moving average, currently at 1,987, fails to act as support, the index is likely headed toward 1,920. Energy prices need to stabilize in order for the market selloff to subside. 

The energy sector continues to plummet, with the Energy Select Sector SPDR ETF (XLE) - Get Report down 5.5% on the year, in just three short trading days, noted Josh Brown, CEO and co-founder of Ritholtz Wealth Management. The selling is also hitting other sectors, like the financials, which are down 4% on the year already, after leading the market higher in 2014. 

The energy and financial sectors make up roughly 24% of the S&P 500, which would explain why the broader market is selling off so much, said Stephanie Link, chief investment officer of TheStreet and co-manager of the Action Alerts PLUS portfolio. Perhaps when earnings start to be released, investors will regain their confidence.

While she sold some of her positions in Ensco (ESV) and SunTrust Banks (STI) - Get Report in the Action Alerts PLUS portfolio, she still likes consumer discretionary, technology and health care stocks. Specifically, she's a buyer of Red Hat (RHT) - Get Report

The good times aren't over, said Andrew Wellington, CIO of Lyrical Asset Management. 

And while there aren't a lot things to be overly excited about it, there also aren't a lot of things to be overly cautious about either. He likes three stocks going forward, AerCap Holdings (AER) - Get Report , Goodyear Tire & Rubber (GT) - Get Report and NCR (NCR) - Get Report

AerCap is an aircraft leasing business that generally has its customers sign six-year to 12-year contracts. It's acquisition of ILFC from American International Group (AIG) - Get Report , was one of "the most accretive deals I've ever seen," Wellington said. It now trades at a very low valuation, as does Goodyear Tire.

Goodyear has seen record margins and record profits now that it focuses on high end tires and products. Lower input costs are also helping, he added. The stock should trade with an earnings multiple equivalent to that of the S&P 500, giving shares 70% to 80% upside. 

The conversation shifted to Twitter (TWTR) - Get Report , as Ross Levinsohn, former interim CEO of Yahoo! (YHOO) , was a guest on the show. He called Twitter one of the most important companies in the industry, as well as a "global newsroom" for its real-time data. Twitter and Yahoo! would make for a "very powerful" combination, considering the strength the entity would have on mobile, content, search and video, he added. Yahoo! needs to return some of its capital to shareholders too, he said. 

For their final trades, Brown is buying the Energy Select Sector SPDR ETF and Link is buying Cigna (CI) - Get Report . Pete Najarian said to buy Eli Lilly (LLY) - Get Report and Jon Najarian is buying Goodyear Tire & Rubber.

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This article is commentary by an independent contributor. At the time of publication, the author held positions in AAPL.