Investigative journalism is a form of journalism in which reporters deeply investigate a single topic of interest, such as serious crimes, political corruption, or corporate wrongdoing. An investigative journalist may spend months or years researching and preparing a report. Practitioners sometimes use the terms "watchdog reporting" or "accountability reporting".

Most investigative journalism has traditionally been conducted by newspapers, wire services, and freelance journalists. With the decline in income through advertising, many traditional news services have struggled to fund investigative journalism, which is time-consuming and therefore expensive. Journalistic investigations are increasingly carried out by news organisations working together, even internationally (as in the case of the Panama Papers and Paradise Papers), or by organisations such as ProPublica, which have not operated previously as news publishers and which rely on the support of the public and benefactors to fund their work.

The growth of media conglomerates in the U.S. since the 1980s has been accompanied by massive cuts in the budgets for investigative journalism. A 2002 study concluded "that investigative journalism has all but disappeared from the nation's commercial airwaves".[1] The empirical evidence for this is consistent with the conflicts of interest between the revenue sources for the media conglomerates and the mythology of an unbiased, dispassionate media: advertisers have reduced their spending with media that reported too many unfavorable details. The major media conglomerates have found ways to retain their audience without the risks of offending advertisers inherent in investigative journalism.