Berkshire Hathaway's Class A stock has fallen below $100,000 for the first time since January 2010 amidst broader market declines and concerns about the health of the economy.

The Class A shares of Warren Buffett's company declined $2,261, or 2.2 percent, to $98,989 Thursday afternoon. The more affordable Class B shares also declined $1.70, or 2.5 percent to trade for $65.52. The Standard & Poor's 500 index fell 3.8 percent.

Over the past year, Berkshire's Class A shares declined nearly 19 percent from $124,865 to yesterday's closing price of $101,250. By contrast, the S&P 500 index that Buffett measures his company's progress against is up about 2 percent over last September's levels.