Shaking things up, if this goes through the two platforms will be combined into one at some point, changing things for some participants. Nasdaq OMX and IntercontinentalExchange unveiled a rival bid to buy NYSE Euronext for about $11.3 billion in cash and stock, a 19 percent premium to an offer made by German competitor Deutsche Boerse. The move, announced on Friday, represents an intense bidding war for NYSE Euronext, whose derivatives trading operations are highly valuable. The new bid could also sit better politically, because the idea of a German company taking over the emblematic NYSE headquarters had stirred some political opposition in the United States. The offer is valued at $42.50 per share, a premium of 19 percent to the agreement proposed by Deutsche Boerse in February, the companies said in the statement.