(Bloomberg) — Merger Monday is back. Traders just aren’t reacting with the usual fanfare.

Energy Transfer Partners LP, Rock-Tenn Co. AT&T Inc. and Post Holdings Inc. are among companies that announced acquisitions Jan. 26 in what may signal another big year for deal making. January is already off to the busiest start in more than a decade, with $157 billion of transactions so far, according to data compiled by Bloomberg.

It’s not all good news for investors. Falling crude prices, the European Central Bank’s quantitative-easing package and the Swiss National Bank’s surprise decision to let its currency appreciate have created large swings in stock prices. That’s making it even more difficult for merger-arbitrage traders to profit than in 2014, when macroeconomic forces began to gouge deal spreads and shrink returns.

“People are being whipsawed,” Sachin Shah, a special-situations and merger-arbitrage strategist for New York-based Albert Fried & Co. said in a phone interview. “Investors want to see more deals, but the macro news is coming so fast and furious this year and it’s having an impact on valuations and risk. It creates a fire-drill mentality, and everyone’s just trying to put out the fires until we get back to normal.”

Because acquisitions are commonly announced on Mondays, the investment community has dubbed the day “Merger Monday.” Traders tend to welcome small flurries of deals, and stocks of both buyers and sellers often rally.

Lost Value

While some dealmakers gained on this Monday’s merger news, shares of companies including Energy Transfer Partners, AT&T and Retail Properties of America Inc. all fell.

Daily moves in the Standard & Poor’s 500 Index, the benchmark for American equity, have doubled from a year ago and the index went 15 straight days with peak-to-trough changes of greater than 1 percent, the longest since 2012. It has already fallen more than 2.7 percent on two separate occasions in 2015, and both times recovered the full loss within a week.

Energy Transfer Partners announced the day’s biggest deal, with its $18 billion agreement to buy all the publicly traded units in Regency Energy Partners LP, a pipeline company that it controls. The parent’s stock slid 6.4 n Monday, while Regency rose by about 5 percent. The deal is the latest attempt to simplify the often complex structures of pipeline companies, and it comes as oil trades near its lowest level since 2009.

Other Deals

Rock-Tenn and MeadWestvaco Corp. said they will merge in a transaction valued at about $9.2 billion to create the world’s second-largest packaging company. It’s the industry’s largest deal in a decade. Rock-Tenn gained 6.1 percent as MeadWestvaco climbed 14 percent.

AT&T fell less than 1 percent after saying it will pay $1.9 billion for companies that operate under the name Nextel Mexico as part of the wireless carrier’s expansion south of the U.S.

On Sunday, Axis Capital Holdings Ltd. agreed to merge with PartnerRe Ltd. combining two reinsurers with a total market value of almost $11 billion. Both stocks climbed Monday.

Until this week, January takeover volume was off to a slower start than many had forecast, said Keith Moore, an event-driven analyst for MKM Partners in Stamford, Connecticut.

“The volatility in the equity markets — a lot of that coming from the oil market — could partially explain that,” Moore said in a phone interview. “When you have prices moving up and down so much in one day, sometimes it’s hard to strike a definitive merger agreement.”

If it starts to “look like things are simmering down like today, I think that makes it a little easier to structure deals,” he said. “And overall I think it will be a favorable environment this year.”

To contact the reporter on this story: Tara Lachapelle in New York at tlachapelle@bloomberg.net

To contact the editors responsible for this story: Beth Williams at bewilliams@bloomberg.net Elizabeth Wollman