CBOE Holdings and Nasdaq OMX Group may scramble to find deal partners as global exchanges’ merger mania returns with a bang.

Germany’s Deutsche Boerse announced on Wednesday it was in advanced talks to buy NYSE Euronext, hours after the London Stock Exchange said it had agreed to buy Canadian stock market operator TMX.

The deals sent shares of exchanges up across the board as investors bet more is to come.

Pressure is mounting on global bourses to seek partnerships to counter the threat from bigger rivals and alternative trading platforms, and to cut costs, analysts said.

“Nasdaq, I think, is probably the odd man out right now,” said Larry Tabb, founder of research and advisory firm Tabb Group. “You would expect Nasdaq to make the next move.”

Nasdaq, given its $5.1 billion market cap and focus on the intensely competitive, low-margin equities business, was more likely to be an acquirer than a target, Tabb said.

Nasdaq might also wait to buy the survivor of two ongoing deals: the London-Toronto deal and a possible merger between Bats Europe and Chi-X Europe, Tabb said.

Still, the LSE-TMX combination could be ambitious for Nasdaq given that it would have a larger market value, and Nasdaq’s shares rallied 6.7 percent on Wednesday, indicating that some investors also view it as a possible target.

The latest deals mark a return of the long-term consolidation trend among exchanges, which was interrupted by the financial crisis.

Singapore Exchange in October agreed to buy Australia’s ASX in a deal valued at $7.8 billion.

In the last 10 years, deal activity between exchanges has totaled $94 billion from more than 600 deals, according to Thomson Reuters data.

“On the one hand they are defensive, to contain costs, and on the other hand, they are on the attack,” said Thomas Caldwell, CEO of Caldwell Securities Ltd in Toronto, which owns shares in most of the major global securities markets. “Exchanges have to act to respond to alternative trading systems, and they also have to act to bring their costs down.”

Shares of CBOE Holdings, which runs the oldest U.S. stock-options exchange, also surged as investors pegged it as an acquisition target.

CBOE is probably an obvious pick in terms of, “if it’s not a consolidator, it’s probably a target,” said Ed Ditmire, an analyst at Macquarie Securities.

CME Group Inc. has long been seen as a potential acquirer for CBOE.