**Overall Market Conditions**: Broad economic trends, investor sentiment, and global events can significantly impact BRK-B.

**Berkshire Hathaway's Earnings**: Strong financial performance, investment gains, and profitability drive up its stock price.

**Investment Portfolio Performance**: The success of Berkshire's major holdings (e.g., Apple, Coca-Cola) affects investor confidence.

**Warren Buffett's Influence**: His decisions, pronouncements, and succession planning are critical factors in valuation.

**Interest Rates**: Changes in interest rates can impact the attractiveness of BRK-B relative to bonds or other investments.

**Book Value**: Investors often use book value as a benchmark to assess BRK-B's price relative to its underlying assets.

**Share Repurchase Programs**: Buybacks can reduce the number of outstanding shares and potentially increase the stock price.

**Economic Moats of Subsidiaries**: The competitive advantages and resilience of Berkshire's operating businesses affect its long-term prospects.