In the pair of notes, UBS's Brian Meredith trimmed the firm's price target for Berkshire's B shares to $245, down from $249. The stock was last trading around $208.22 on Wednesday. UBS also lowered its 12-month price target for the A shares to $367,000, down from $373,000. A-shares were last trading around $311,450.
UBS maintains a buy rating on both the A and B shares of Berkshire.
In the notes, Meredith also lowered his second-quarter earnings estimates for Berkshire Hathaway, in part, because of anticipated weakness in railroad operator BNSF Railway.
Meredith expects Berkshire to deliver EPS of $10.42, down from $10.52 for the B-shares, and EPS of $15,631, down from $15,868, for the A-shares.
"We anticipate weaker performance in BNSF for 2Q19 stemming from a decline in volumes across the industry, though it remains difficult to determine whether this is due to trade tensions versus broad cyclical weakness,” Meredith wrote. “For BNSF we estimate volumes declined 3.8% [year over year] in the quarter, driven primarily by intermodal and agriculture.”
UBS cut its second-quarter growth estimates for BNSF to 1%, down from 9%.
"We had originally anticipated that rail volumes would recover from the Midwest floods that occurred in them first quarter; however, residual impact of the floods, as well as softness in industrial demand, is likely to put continued downward pressure on revenue growth," hewrote.
One of the risks to railroads is lower oil prices, which results in slower growth or no growth in the energy space, which ultimately means weaker volumes to transport by rail.
Another area likely to contribute to lower earnings is the reinsurance side of the business.
In the first half of 2019, Berkshire Hathaway has underperformed the broader market, gaining 1% compared to the S&P 500's 20% rise.
"This may be partially due to some dissatisfaction with commentary around share repurchase from the annual meeting, in which Buffett didn't necessarily commit to a large-scale buyback program," Meredith wrote.
UBS is predicting around $10 billion in share repurchases during the second quarter.
Berkshire reports earnings results on Friday, August 2.
Julia La Roche is a finance reporter at Yahoo Finance. Follow her on Twitter.