Ending an eight-day string of devastation, the Dow staged a 936-point rally Monday.

The 11% rise to 9,387.61 was the biggest single-day percentage gain since 1933.

Nearly every media company came along for the ride as investors balanced bargain-hunting with genuine enthusiasm for the government’s stepped-up relief efforts.

Of particular note to media dealmakers was the kernel of hope that government investment in major banks would ease the credit crunch that has constricted the flow of capital for at least a year.

Disney shares climbed 16% to $16.72. News Corp.’s rose 20% to $10.18. Time Warner stock went up 13% to $10.40.

Another major beneficiary of the rally was Viacom.

The conglom’s stock tumbled 17% Friday, when Sumner Redstone disclosed the sale of 17 million class B shares in CBS and 7 million class B shares in Viacom. On Monday, the stock rebounded, gaining 23% to $21.06.

Redstone’s National Amusements officially wrapped on Monday its sale of $233 million in nonvoting shares that it owned in CBS and Viacom in order to help retire debt. It had earlier projected the sale would total $400 million.

Prompted by the sale disclosure, CBS and Viacom lowered third-quarter guidance Friday, noting difficulties in the ad biz and a goodwill writedown of CBS TV stations.

National Amusements, which is technically the parent company of CBS and Viacom and is a vehicle for Redstone’s $1.9 billion controlling stake in the two, said it will not sell any more shares.

While the day’s green numbers meant plenty to celebrate on Wall Street and in corporate suites, a growing anxiety about media firms’ sensitivity to advertising revenue kicked in. Beyond Viacom and CBS, two of the most vulnerable, analysts lowered estimates for Disney, News Corp. and Sinclair Broadcasting.

Sinclair reported preliminary third-quarter results Monday, with revenue of $150 million coming in flat compared with the year-earlier quarter. Final numbers will be released Nov. 5.

One interesting detail many media and entertainment watchers hope doesn’t become commonplace during the upcoming earnings season, which peaks later this month: Local ad buys by political candidates are much lower than initially planned.

“Due to the ongoing volatility in the marketplace and its impact on advertising budgets, we are expecting net broadcast revenues for the fourth quarter 2008 to be down mid-to-high single-digit percents as compared to the fourth quarter 2007,” said Sinclair prexy-chief exec David Smith.