Updated from 4:09 p.m. EDTBlue chips overcame a midsession stumble and bolted into the close Tuesday, while a gain in Apple ( AAPL) propped up the tech sector. The Dow Jones Industrial Average ended a volatile session -- one that saw the index briefly dip into negative territory -- with a gain of 109.26 points, or 0.81%, to 13,676.23. A 2.9% decline in Wal-Mart ( WMT) put some pressure on the index, but it wasn't enough to keep the average from rallying. The S&P 500 added 13.26 points, or 0.88%, at 1519.59. Meanwhile, the tech-heavy Nasdaq Composite surged 45.33 points, or 1.65%, to 2799.26, thanks to strong earnings from Apple. Following the last close, the company blew away fiscal fourth-quarter estimates with its latest report, prompting several analysts to bump their stock price targets higher. UBS has now assigned a target of $220, while JMP Securities raised its target to $210 from $160. Shares of Apple jumped $11.80, or 6.8%, to end the day at $186.16. "A lot of the negative news was wrung out of the market today, as some positive earnings reports alleviated fears," said Edgar Peters, chief market strategist with Pan Agora. "A lot of these earnings reports showed that the consumer was still spending, which is good news. We had been oversold and people were too pessimistic, so today we righted things again."