Google’s $500 Million DOJ Fine Is Reportedly Related To Online Pharmacy Ads

Mystery no more: The WSJ says the $500 million fine Google (NSDQ: GOOG) disclosed it might have to pay earlier this week is related to a DOJ investigation over online pharmacy ads the search engine ran. On Tuesday, Google said it might have to pay the penalty, but it wouldn’t say why.

According to the WSJ report, the DOJ is looking into whether Google knew it was running ads from illegal online pharmacies based in the U.S. and Canada. Google has taken steps in the past to ensure it is only taking ads from above-board pharmacies; in February 2010, for instance, it updated its AdWords policy so that only pharmacies in both countries accredited by professional groups could run ads.

Google has implied that it’s on the verge of settling the investigation, saying in an SEC filing earlier this week that it would take a $500 million charge “in connection with a potential resolution” of the investigation. As my colleague Joe Mullin wrote earlier this week, if Google does in fact shell out $500 million, it will rank among the biggest tech-company of fines all time.