Fox needs to raise its offer of 10.75 pounds per share for the 61 percent of the British pay-TV company it doesn’t already own, in order to challenge Comcast’s 12.50 pounds per share bid. Comcast, which already won U.K. approval for its Sky approach, has a deadline of Friday to put the 22 billion pound ($29 billion) proposal to Sky shareholders under U.K. takeover rules....The tussle over Sky is part of a wider bidding contest between Comcast and Walt Disney Co. for the bulk of Rupert Murdoch’s media empire, as each tries to scale up to take on streaming competitors Netflix Inc . and Amazon.com
Although it's formally an arbitrage strategy, purists would argue that it's not a pure arbitrage as it incorporates speculative aspects and is not as riskless as other strategies such as convertible arbitrage which fully hedges deltas:
The main basis in a stock-for-stock acquisition revolves around the idea that the target's stock will often trade at a lower market price compared to the exchange ratio that will apply once the deal is closed. Traders will purchase the target's stock and receive an excess value of the acquirer's stock when the deal is closed.
To hedge risk, traders will short the same number of the acquirer's shares based on the exchange ratio.
The objective is to capture the spread between the target's share price at market and the closing price based on the exchange ratio set by the acquirer. Spreads can be between 5-10% (median) for deals that close upwards of 55 days.
Unlike other arbitrages, risk arbs can be done quite easily, but like all other strategies, can also become more efficient and complex if done professionally.
Risk arb funds can also be good diversification for a portfolio as they often generate superior risk adjusted returns in poor markets.