Shares of Joy Global Inc., which makes heavy equipment for mining, rose Thursday after its board increased a share repurchase program by $1 billion to $2 billion.
The board also extended the buyback plan's expiration to the end of 2011, from the end of 2008.
Joy Global, which had roughly 107.8 million shares outstanding as of Aug. 29, said it plans to buy back shares under the first $1 billion authorization before the end of the year.
Repurchasing stock takes a company's shares out of circulation, boosting the value of existing shares and fattening profits measured per-share. Companies usually repurchase shares when they feel their stock is undervalued.
Shares rose $5.18, or 11.5 percent, to close at $50.15. In the last 52 weeks the stock has ranged from $42.10 to $90.