Google has passed Exxon to become the second most valuable U.S. company by market capitalization.

According to FactSet data, the Internet company's market capitalization surpassed that of oil company Exxon Mobil Corp. last week. As of Friday's market close, it sat at $395.42 billion compared with the oil company's $392.66 billion.

Market capitalization is the number of outstanding shares multiplied by their value.

Shares of Google Inc. have been on a steady climb since the beginning of 2013, gaining 66 per cent.

Meanwhile, Exxon's have risen just five per cent. Since the beginning of this year, they've lost about 10 per cent of their value.

Both companies trail Apple Inc.'s market capitalization of $463.55 billion.