This isn't exactly media bias, but since the myth of the conservative corporation is one of my personal favorites to demolish, I couldn't help but link to a Human Events study showing that conservative groups get far less money from Fortune 100 companies than liberal groups do. Here's an excerpt:
Liberal blogger David R. Mark recently wrote, “Those that call themselves ‘compassionate conservatives’ would never think to touch their fat-cat supporters. It’s much easier to spin the ‘economic benefits’ of helping huge corporations fatten their bottom lines.” Liberal academic Thomas Frank, in his book What’s The Matter With Kansas?, claims that the corporate world “wields the Republican Party as its personal political sidearm.” Both Mark and Frank express a common view that corporations are major funders of the political right, and that when corporations make contributions to nonprofit advocacy groups they give to groups on the right because those groups are pro-business.
On its face, this makes sense. After all, conservatives generally support lower taxes, less government regulation, and freer trade, public policies that are supposed to coincide with the interests of corporations. Why wouldn’t corporations eagerly fund their political supporters? In a Washington Examiner editorial, Professor Thomas F. Schaller lamented the “‘infrastructure gap’ that persists between the well-funded and highly organized Republican right and the relatively underfunded and generally disorganized Democratic left.” [...]
If the political right and major corporations are as closely aligned as popular perception suggests, then the corporate foundations examined in this report ought to be more generous to groups on the political right than those on the political left. That’s not what we found.
In this analysis, we examined only those Fortune 100 companies that operated nonprofit charitable foundations that made grants to groups we identified as on either the political right or left. That reduced the number to 53 corporate foundations. (See page 20.) We examined the most recent tax- return filings for these foundations (IRS Form 990) and compiled the dollar values for grants and matching gifts to left-wing groups and right-wing groups.
The results are the exact opposite of the common perception. The Fortune 100 foundations gave more money to the political left. In fact, the grant-making was lopsided: The political left received nearly $59 million, while the political right received only about $4 million, a ratio of 14.5 to 1.
The article goes on in much further detail, offering hypotheses on why the left-right disparity exists, as well as a detailed break-down of the businesses' giving. It's well-worth reading.