Shares of

JDS Uniphase

(JDSU)

traded furiously late Wednesday, as investors scarfed up shares of the optical equipment maker ahead of its addition to the

S&P 500 index and its earnings report.

JDS, which has been on a buying spree in the high-profile Internet equipment business, posted strong fiscal fourth-quarter earnings Wednesday afternoon, beating Wall Street estimates by 2 cents. Earnings more than doubled from a year ago, to $114 million, or 14 cents a diluted share, from $41 million, or 6 cents a share, a year ago. Revenue jumped to $524 million from $192 million a year earlier. Latest-period results exclude the effect of various merger-related costs.

By the end of the day, some 132 million shares of JDS had traded, representing around six times' average daily volume. The stock climbed 5 3/4, or 4.4%, to 135 15/16.

Merrill Lynch

has estimated that S&P 500 index funds would need to buy 57 million JDS shares at the close.

Interestingly, shares of

SDL

(SDLI)

, which JDS announced July 10 that it would acquire, declined. Over the past three sessions, the spread between JDS and SDL has widened appreciably. It is difficult to tell if this is because investors reckon the deal is less likely to go through because of regulatory hurdles, or if arbs were simply unwilling to play the indexing game.