Personal Finance Mary Buffett's tips for budding value investors: sound research and patience Updated : October 03, 2020 03:06 PM IST As to the rules, she followed while investing, Mary said the most important thing was to understand the company’s history and not just its balance sheet. She said she never invests in initial public offerings. Like Warren, Mary says her holding period for stocks is "forever." Subscribe to Moneycontrol PRO at just Rs.33/- per month for the first year. Use code SUPERPRO. Limited period offer. Available on Web and Android.