Broadvision (BVSN) - Get Report was up 11% to $26.38 in early trading on the announcement late Monday that the software maker would be added to the S&P 500.

BroadVision will replace

PaineWebber

( PWJ), which is being taken over by Swiss bank giant

UBS

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.

S&P 500 index funds will have to buy about 17 million shares of BroadVision when it is added to the index after the close on Monday, according to

Merrill Lynch's

equity derivatives group -- about a day and a half of normal trading volume in the stock. Over 9 million PaineWebber shares will need to be sold.

Typically, some traders will buy a stock ahead of its addition to the S&P. Moreover, index funds will contract with brokerages to amass shares for delivery on the addition date.