 Insider buying can be an encouraging signal for potential investors. Beneficial owner Berkshire Hathaway made a huge purchase last week. A director took advantage of a coronavirus vaccine contenders secondary offering.Conventional wisdom says that insiders and 10 owners really only buy shares of a company for one reason -- they believe the stock price will rise and they want to profit from it. So insider buying can be an encouraging signal for potential investors, particularly during periods of uncertainty.Insiders continued to add shares despite overall market volatility and global economic gloom. Here are some of the most noteworthy insider purchases reported in the past week.Formula One Group Liberty Media Formula One NASDAQ: FWONA saw 10 owner Berkshire Hathaway Inc. NYSE: BRK-A add nearly 3.17 million shares of this motorsport company to its stake. At per-share prices ranging from 33.07 to 37.05, that totaled almost 112.42 million.Shares of this Liberty Media subsidiary popped more than 9 in last weeks trading to end at 33.82 apiece, within the purchase price range above. The share price is up about 75 since its year-to-date low during the pandemic panic selling back in March. The analysts consensus target price is up at 45.53.Avis Budget Beneficial owner SRS Investment Management purchased almost 500,000 Avis Budget Group Inc. NASDAQ: CAR shares of this New Jersey-based company last week. Share prices ranged from 18.57 to 20.59 apiece, and the total for these transactions was more than 9.88 million.Competitor Hertz Global recently filed for bankruptcy and will be delisted from the New York Stock Exchange. Avis shares ended last week up nearly 29 to 21.53, above the purchase prices mentioned above. The share price is more than 77 higher since its year-to-date low in March.See Also: What You Need To Know About Modernas Insider SellingDynavax A Dynavax Technologies Corporation NASDAQ: DVAX director took advantage of a secondary offering last week. He indirectly bought a million shares for 5 apiece, which cost him 5 million. He is also a director at Mersana Therapeutics Inc NASDAQ: MRSN and bought more than 3 million of those shares back in April.Dynavax is among those companies in a race for a vaccine for COVID-19. Its shares soared more than 19 last week and closed most recently at 6.12 a share. Its now about 154 higher than the year-to-date low in March. The consensus price target is up at 16, though only two analysts were surveyed.In addition, note that there was some amount of insider buying at Green Dot Corporation NYSE: GDOT, Jazz Pharmaceuticals PLC NASDAQ: JAZZ and Royal Caribbean Cruises Ltd NYSE: RCL last week as well.See more from Benzinga Benzingas Bulls And Bears Of The Week: Amazon, Disney, Netflix And More Notable Insider Buys This Past Week: Berkshire Hathaway, Sysco And More Barrons Picks And Pans: Dropbox, Slack, Starbucks And MoreC 2020 Benzinga.com. Benzinga does not provide investment advice. All rights reserved. 