bluebird bio soars on revised offer from Carlyle, SK Capital Partners

Shares of gene therapy maker bluebird bio BLUE.O rise 50.5% to $4.98 premarket

Bluebird bio says its board approved the revised merger deal with investment firms Carlyle CG.O and SK Capital Partners

Under terms of the amended deal, bluebird stockholders can elect to get $5 per share in cash or the original offer of $3 per share in cash plus a contingent value right of $6.84 per share that is payable upon achievement of a net sales milestone

New offer price of $5 represents a 51% premium to BLUE's last closing price

"The amended offer price provides an alternative for stockholders who would prefer greater upfront cash consideration instead of the potential upside of the CVR", the cos say

Up to last close, stock down 60.3% YTD