The “when-issued” trading will set stock prices and values for the two companies when they officially split on June 28. The publishing company’s Class A shares, trading under the ticker NWSAV, rose 3.4 percent to $15.80 at the close in New York, compared with the opening price. The entertainment Class A stock, FOXAV, gained less than a percent to $28.35, compared with the opening price.

News Corp.’s television and movie company, which will be renamed 21st Century Fox after the split, is worth about $65 billion. That compares with $9.1 billion for the publishing side. News Corp. Chief Executive Officer Rupert Murdoch agreed to the breakup last year after investors pressured him to unshackle the two entities.

“People are going to be making the decision about whether they keep both, or shed one and keep the other,” said Evan Lucas, a Melbourne-based markets strategist at trading-services provider IG Markets Ltd. “There will be lots of volatility in the trading until the official split takes place at the end of next week.”

Investors get one share in the publisher, which will keep the News Corp. moniker, for every four they already held in the old company, which will be renamed after the split formally takes place next week. Shareholders backed the spinoff at a meeting last week.

Times, Sun

The new publishing company includes the Wall Street Journal, the New York Post, Australia’s biggest newspaper publisher, and the Times and Sun in the U.K., as well as a half share of Australia’s largest pay-television operator, Foxtel. HarperCollins book publishers and Amplify, a digital-education business led by former New York City schools chancellor Joel Klein, round out the portfolio of the new News Corp.

The company said last month it will write down the value of its publishing business by as much as $1.4 billion, blaming slowing cash flow from its Australian and U.S. newspapers.

Robert Thomson will be chief executive officer of the publishing group, with Murdoch serving as chairman. It will start off with $2.6 billion in cash and approval to buy back $500 million worth of stock after the split.

Murdoch will be chairman and CEO of 21st Century Fox and his sons James and Lachlan will be on the board of both companies.

News Corp. competes with Bloomberg News parent Bloomberg LP in providing financial news and information.