Apple, the world’s most valuable company, added more worth in one day than the market cap of nearly 400 individual companies in the S&P 500.

The smartphone maker’s shares surged 6 percent to a new all-time high at Wednesday’s open, a day after it reported better than expected earnings. The gain represented $48.1 billion of additional value for Apple shareholders to an approximately $830 billion total market value.

The single day increase is more than the market value of Ford Motor and 392 companies in the S&P 500, according to FactSet.

Apple’s stock gain was reduced to up 4 percent midday Wednesday.

Apple’s cash pile rose to a record $261.5 billion, which is enough to buy Wal-Mart outright at its $243 billion market cap.

The technology company has been one of the best-performing large-cap stocks in the market. Its shares rallied 29.6 percent year to date through Tuesday versus the S&P 500’s 10.6 percent return.