U.S. stocks had their best week in 2014 last week, with the Standard & Poor's 500 Index and the Dow Jones Industrial Average both gaining 2.3%. Most industry pundits are attributing the market's performance to a spade of strong earnings reports and reassurance from new Federal Reserve Chair Janet Yellen that she plans to stay the course on the gradual stimulus tapering policy set by her predecessor.

The three best-performing stocks on the S&P 500 last week were Trip Advisor (TRIP -3.16%), Goodyear Tire & Rubber (GT -1.52%), and NVIDIA (NVDA -1.99%).

Before we home in on the reasons for these stocks' weekly jumps -- which ranged from 12.9% to 18.3% -- it's worth noting that all three have also been winners over the one-year period, returning nearly 95%, 90%, and 44%, respectively.

Trip Advisor: Up 18.3%
Trip Advisor's stock price jump was due to its Feb. 11 release of fourth-quarter 2013 earnings results that beat analysts' revenue estimates. The company posted revenue of $212.7, up 26% from the year-ago period and topping the consensus of $205.6 million. Adjusted earnings decreased 28% to $0.21 per share, but were in line with estimates.

The online travel company's strong revenue performance was powered by its display ad and subscription and transaction businesses, which grew 46% and 53%, respectively. Its bread-and-butter click-based ads, which accounted for 68% of total revenue, also performed solidly, rising 17%.

The company's heavy TV ad spending, along with a general boost in its sales and marketing efforts, negatively affected earnings.

Trip Advisor's traffic surged 50% in the quarter, pushing the number of unique monthly visitors to 260 million. Another positive was that the company's meta-display ad platform, which it recently rolled out, performed better than expected. This feature allows users to compare pricing and availability information for hotels and other travel products on the Trip Advisor site.

The Motley Fool CAPS community likes Trip Advisor, rating it four stars (out of five).

Goodyear Tire: Up 13.7%
Goodyear Tire's stock price leap can be attributed to its reporting of fourth-quarter 2013 earnings that were higher than analysts' estimates, and the reaffirming of its guidance for 2014 through 2016.

The tire manufacturing giant, which reported on Feb. 13, posted adjusted earnings of $0.74 per share, up 90% from the year-ago period, and smashing the consensus estimate of $0.63. Revenue decreased 5% to $4.8 billion, falling short of the $4.96 consensus.

Investors seemed non-plussed about the slight revenue drop, as it was largely due to weakness in the company's third-party chemicals business and foreign currency translation. Goodyear's core tire business performed solidly, with worldwide unit volume increasing 2% to 40.7 million. North American results were particularly strong, with tire sales rising 3%, which includes a 7% rise in new tires sold to automakers and a 1% rise in replacement tires. A strongly rebounding U.S. new vehicle market over the past couple years has been "driving" new tire sales.

Investors were no doubt also cheered by news that the company's pension obligations are now fully funded.

The Motley Fool CAPS community rates Goodyear two stars (out of five).

NVIDIA: Up 12.9%
On Feb. 12, NVIDIA reported its fiscal 2014 fourth-quarter results for the period ending Jan. 26, surprising the market with both revenue and earnings beats.

The company, which develops graphics chips, grew revenue 3% to $1.14 billion, easily topping the consensus estimate of $1.05 billion. Earnings per share fell 11% to $0.28 to $0.25 but significantly beat the consensus of $0.18.

NVIDIA's much-better-than-expected results were driven by the company's strong performance in its GPU segment, which generated revenue of $947.0 million, up 14% from the year-ago period. This segment's high-end GeForce GTX graphics chips, which are popular with hard-core gamers, performed particularly well, with sales increasing nearly 50%.

Revenue in NVIDIA's Tegra mobile processors segment dropped 37% because of tough competition in the tablet and smartphone space. However, the company increased its sales of the mobile chips to automakers, for use in entertainment and navigation systems. Many analysts and investors are particularly enthusiastic about the company's prospects for its super-powerful Tegra K1 chip, set to launch this year, in the auto and the higher-end, higher-performance smartphone and tablet spaces.

The Motley Fool CAPS community is game for NVIDIA, rating it four stars (out of five).