The American share, although clearly the largest, has not changed since 1980.
Nearly four million shares changed hands, as the stock closed at 13 3/8.
More than 13 million shares changed hands, the most since October.
Coal's share of the power generation market has changed little in recent years, standing at about 51 to 52 percent.
Nearly 1.9 million shares changed hands, with about half coming from big investors.
Among the three stocks, nearly 13 million shares changed hands.
A year ago, the shares changed hands at 45 cents a share.
Some 2.05 million shares changed hands, more than double the daily average of 835,200.
The issue was the most active of the day, with 8.1 million shares changing hands.
But more than 1.1 billion shares changed hands on the Nasdaq market.