Bloomberg broke the news on Wednesday July 3rd, 2019 that Broadcom is in talks to buy struggling Symantec. This is a terrible idea on many fronts and AVGO closed down 3% on the news. I believe that investors do not want this semiconductor company to waste $20 billion on a cybersecurity company (and why pick the one that seems to be struggling the most?). Certainly makes sense that we head lower over the next few days/weeks.
A few references: AbbVie buying Allergan - stock closed down 15% Salesforce buying Tableau - stock closed down 3% (but it hasn't dropped further)