Shareholders in oil and gas production firm Berry Petroleum ( BRY) are having a great year. Since LinnCo ( LNCO) announced on Feb. 21 that it would be buying the larger E&P for $4.17 billion in stock, shares of BRY have climbed close to 40%. But merger arbitrage aficionados take note: There's still a healthy 6% premium in the deal. >>5 Stocks Ready to Rocket Higher in April Berry owns oil and natural gas wells spread across six sets of assets spread from Texas to California. That U.S. focus means that Berry's assets don't have the potential upside of overseas production operations, but they also don't carry any geopolitical risk either. The firm's timing proved unfortunate heading into the financial crisis of 2008, as Berry levered up its balance sheet to buy a major acquisition in Texas -- but management's decisions to unwind positions in favor of balance sheet liquidity should be appreciated. Bear in mind that after this merger legacy Berry will still make up the lion's share of the combined firm's assets. While the 6% of wiggle-room in the acquisition premium presents a potentially attractive profit for betting on this deal being consummated, investors should remember that the premium is there because at least some people think that the combination won't happen.