Constituent Stock Performance: The price mirrors the performance of Berkshire Hathaway's Class B shares (BRK.B). Positive BRK.B movement usually lifts BRF.US, while negative impacts it.

Market Sentiment: General optimism or pessimism towards the stock market influences BRF.US. Bull markets tend to boost it; bear markets often drag it down.

Economic Conditions: Strong economic growth typically favors BRF.US as Berkshire's diversified holdings benefit. Recessionary environments can negatively affect it.

Interest Rates: Interest rate hikes can sometimes dampen investor appetite for stocks like BRK.B, thus affecting BRF.US. Lower rates may have the opposite effect.

News & Events: Major announcements concerning Berkshire Hathaway, such as earnings reports, acquisitions, or CEO commentary, can trigger price swings in BRF.US.

ETF Supply & Demand: High demand for BRF.US can drive up its price, while increased selling pressure may lower it, irrespective of BRK.B's intrinsic value alone.