Investor Warren Buffett says the acquisition frenzy on Wall Street is making it hard for him to find deals at the right price, but his Berkshire Hathaway conglomerate recorded a $29 billion gain because of the tax reforms Congress passed.

In his annual letter to shareholders Saturday, Buffett mixed investment advice with details of how Berkshire's many businesses performed.

Buffett says a 10-year bet he made with a group of hedge funds shows why investors should be wary of fees and focus on investing regularly for the long term.

Buffett says the asking prices for potential acquisitions reached an all-time high in 2017. That kept Berkshire from making the kinds of big deals Buffett prefers.

So Berkshire held nearly $116 billion in cash and short-term bonds at year end.