Require all government officials, media companies, and their employees to submit their buy and sale orders in real time. As well as a running total of their holdings. This would include any and all forms of investments.
There is way too much to gain personally in pushing for government policy and writing negative/positive news articles.
This would create a clear picture of how and why policies and articles are written. A small section detailing the related stock, land, and other investments for all involved should be included at the start of the document.
For example if a media company held shares of big pharma, the writer of the medical related article held shares in a drug research company, and an affiliate who was paying for the article to be written is invested heavily in both, this small section at the top of the article would give a clear picture of why the article was written to the reader, and who was to gain.
Similarly, someone at the EPA who is heavily invested in one chemical company, and bans a competitive product needs to detail that up front to show their conflict of interest. Additional scrutiny or removal from office could be added for repeat offenders if they were found to be acting not for the good of the people, but for the good of their bank accounts.