White Mountains Insurance Group, Ltd WTM

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White Mountains Insurance Group, Ltd. Common Stock · Company · NYSE

Announcement types: (default: consequential filings)
Results & current reports
Capital markets
Ownership & governance

USD closing-price chart (daily close from yfinance · Last year)

USD 1791.35 → 2182.32 · 21.8%
2319.4101984.9551650.500 1,2 3 4 5 6,7 8 9 10 11 12 13 14 15 16,17 18,19 20 21 22 Jul 25Oct 25Jan 26Apr 26Jul 26

Numbered dotted lines mark the filtered filings under Announcement Events below.

Price & SEC Filing History 22 Jul 2025 — 23 Jul 2026 (Last year)

Daily NYSE prices are sourced from yfinance. Yellow highlighting marks an intraday rise or a gap up between adjacent trading sessions. SEC acceptance times are converted to US Eastern time: pre-market filings appear below that day’s OHLCV row; filings accepted after the 09:30 ET open appear above it. The SEC does not publish an exact first-public-availability timestamp, so acceptance time is the best available proxy.

No data yet
2192.0000 2211.0400 2161.5901 2182.3201 12,975
2201.5100 2222.5000 2167.9800 2193.2600 13,500
2214.5000 2249.0500 2209.7300 2211.2200 16,100
Weekend
Weekend
2198.2400 2239.9500 2198.2400 2211.5200 12,600
2126.1001 2203.6399 2126.1001 2196.4800 21,200
2162.6001 2173.7500 2125.8401 2139.7300 15,300
2162.5100 2187.9299 2146.3501 2167.7900 21,200
2192.7000 2203.3601 2157.5000 2174.9600 16,000
Weekend
Weekend
2197.9900 2199.1499 2165.0901 2181.1899 18,500
2167.0200 2189.8201 2159.7300 2185.2300 25,900
2164.9800 2179.5901 2147.5000 2167.2500 18,400
2176.0000 2198.8701 2161.8999 2165.8501 14,300
2165.2600 2182.8999 2145.3201 2166.2700 14,600
Weekend
Weekend
No trading
2090.0000 2186.8101 2068.6001 2173.8101 25,500
2077.5000 2101.1001 2050.0000 2064.0400 17,600
2075.6001 2098.5000 2057.3401 2073.3899 16,700
2085.7900 2104.7900 2064.6399 2090.9399 13,200
Weekend
Weekend
2023.7900 2096.5601 2023.7900 2096.5601 26,300
2021.7800 2048.6599 2009.0200 2019.7000 14,400
2026.7500 2044.0400 2006.1500 2022.4100 13,800
2015.3600 2028.3400 2001.9900 2023.6300 16,400
2023.0300 2035.0000 1999.8400 2010.7500 13,200
Weekend
Weekend
No trading
1997.3600 2019.8900 1990.7800 2013.3600 25,500
2021.6000 2045.5000 1990.0000 2003.4900 21,600
2037.7600 2051.6599 2010.0000 2032.3700 20,700
2026.1000 2059.6201 2000.3500 2030.6400 31,000
Weekend
Weekend
1995.5000 2030.0000 1991.3000 2024.0500 17,700
2021.1000 2041.4200 1987.0000 1989.5400 17,000
2014.3500 2037.7900 2006.1500 2018.8900 23,500
2029.5000 2050.0000 1991.2900 2004.7600 26,500
2060.0000 2070.0000 2020.0300 2023.7000 29,200
Weekend
Weekend
2016.8000 2084.7100 2016.8000 2065.1399 22,300
22 · 8-K Pre-market · 08:17 ET 8-K ↗
2035.0000 2065.0000 2010.5400 2015.5400 29,900
2050.8101 2066.0601 2017.9800 2034.0200 45,000
2060.0300 2087.9099 2050.6201 2050.8101 23,500
2052.2500 2077.2000 2052.2500 2062.0300 24,200
Weekend
Weekend
2093.1399 2096.5500 2060.9199 2064.8201 25,800
2090.3899 2106.0500 2072.0100 2084.3101 23,500
2138.9700 2159.0000 2094.4700 2101.9399 27,700
2140.3999 2166.0500 2129.1699 2129.1699 16,900
No trading
Weekend
Weekend
2136.8401 2159.0000 2136.8401 2146.8501 16,600
21 · 8-K After-hours · 16:21 ET 8-K ↗
2130.1299 2152.1799 2130.0300 2139.0901 22,400
2152.0500 2175.0000 2142.5000 2144.8101 18,200
2127.2700 2159.0000 2125.0200 2144.1899 29,100
2139.0000 2177.0000 2121.0300 2138.3501 17,900
Weekend
Weekend
2119.0701 2149.9900 2105.0000 2136.7600 21,200
20 · 8-K Pre-market · 09:02 ET 8-K ↗
2128.9099 2196.0901 2096.2300 2112.7200 27,700
2105.1399 2150.0000 2105.1399 2119.9099 23,000
2141.6799 2162.0000 2099.9399 2109.2000 22,400
2143.0000 2173.1101 2110.0000 2133.5801 21,000
Weekend
Weekend
2103.8999 2136.4500 2075.0500 2128.3999 18,800
2080.0000 2106.2800 2050.0100 2092.5000 26,200
2151.3000 2176.5801 2071.8799 2080.0000 38,300
19 · 10-Q Pre-market · 08:31 ET 10-Q ↗ 18 · 8-K Pre-market · 08:20 ET 8-K ↗
2173.3701 2193.7100 2147.7700 2151.6699 17,300
2153.8701 2203.0000 2132.7600 2167.4099 26,800
Weekend
Weekend
2213.0000 2216.5200 2158.1799 2163.5000 19,500
2201.0901 2235.0000 2190.6599 2231.9900 10,900
2261.2900 2270.2100 2188.4399 2206.0000 12,700
2284.0000 2303.4800 2256.5701 2263.6899 16,500
2260.6001 2286.6599 2245.3101 2267.5601 16,000
Weekend
Weekend
2279.5400 2279.5400 2243.9399 2259.2700 15,300
2283.3201 2301.5300 2268.1499 2285.3899 9,400
2292.8701 2292.8701 2261.1001 2269.1899 14,700
2278.1001 2290.9700 2261.0300 2276.3401 10,200
2309.9600 2326.4500 2275.0100 2275.0100 14,100
Weekend
Weekend
2292.2000 2333.0000 2270.0500 2319.4099 14,200
2290.7900 2300.5000 2273.2400 2294.7200 10,800
2301.1001 2310.1201 2280.0000 2291.4600 15,900
2282.2000 2318.5701 2282.2000 2300.0000 17,500
2280.0801 2307.2500 2254.2200 2297.9900 15,000
Weekend
Weekend
2307.1001 2307.1001 2266.6201 2301.1399 19,800
2277.2200 2325.7800 2255.0000 2309.9199 17,100
2235.4399 2290.6599 2205.0000 2277.2100 17,600
2192.9600 2242.0000 2192.9600 2215.7300 15,900
2169.3101 2206.2400 2067.2100 2203.9600 27,400
Weekend
Weekend
No trading
2176.3999 2191.1899 2156.0000 2169.7600 18,000
17 · 8-K After-hours · 16:21 ET 8-K ↗ 16 · DEF 14A After-hours · 16:00 ET FORM DEF 14A ↗
2197.2000 2206.2500 2160.0000 2178.4399 22,200
2212.6299 2224.1101 2163.4099 2196.9600 25,100
2164.3899 2210.8601 2150.8000 2193.8601 14,800
Weekend
Weekend
2219.2700 2223.0000 2134.6799 2153.8601 19,200
2185.5100 2224.5100 2185.5100 2220.7100 10,900
2219.6399 2231.5701 2196.9600 2205.5100 13,400
2169.0000 2220.5601 2152.1599 2211.9099 16,500
2178.9600 2205.4199 2160.9099 2162.9900 19,100
Weekend
Weekend
2190.0000 2205.9900 2155.0000 2155.0100 22,600
2191.6001 2206.5601 2159.7700 2181.1599 22,200
2202.6699 2220.0100 2184.9399 2185.0100 16,500
2206.1001 2246.0000 2206.1001 2206.8101 17,500
2209.9900 2230.0000 2193.5200 2199.6899 17,500
Weekend
Weekend
2199.8601 2217.6799 2190.5801 2194.7000 11,400
2195.2000 2216.4299 2126.2600 2182.0500 17,300
2219.3601 2237.0000 2190.0000 2212.1399 25,000
2145.1899 2236.7000 2100.0000 2223.4600 26,200
2174.8000 2180.8999 2108.8000 2148.6499 28,400
Weekend
Weekend
2165.7000 2208.3701 2134.0000 2165.6001 21,700
2213.4500 2234.8501 2181.3101 2188.9399 19,900
2218.0100 2240.0601 2196.3301 2223.7900 20,200
2226.3899 2239.8301 2179.0000 2215.0901 17,000
2210.0000 2259.2600 2210.0000 2244.1399 24,900
Weekend
Weekend
2217.4399 2239.0000 2185.0000 2220.5100 21,700
15 · 10-K Pre-market · 09:21 ET 10-K ↗ 14 · 8-K After-hours · 17:19 ET 8-K ↗
2219.5901 2264.7000 2214.0000 2222.9700 17,700
2223.5000 2249.8000 2195.0000 2220.2800 19,500
2197.0801 2228.9800 2185.5000 2223.4199 17,200
2235.0000 2240.0000 2182.3401 2189.3401 14,600
Weekend
Weekend
2208.0000 2232.0500 2184.4399 2228.1299 8,600
2204.7900 2225.0000 2173.1599 2201.2300 16,200
2232.2200 2232.2200 2193.6299 2202.1201 13,300
2195.7600 2246.8799 2184.3000 2230.8301 17,800
No trading
Weekend
Weekend
2178.5701 2193.1399 2140.0000 2188.0701 12,900
2177.6899 2200.0000 2144.0000 2182.0100 20,300
2129.1201 2143.8401 2080.0000 2143.8401 15,400
2098.2800 2130.2100 2078.3401 2114.1001 21,200
2181.4700 2202.5000 2077.7100 2098.7800 24,700
Weekend
Weekend
2151.0000 2232.5000 2147.8501 2185.0000 22,900
13 · 8-K Pre-market · 08:21 ET 8-K ↗
2078.4199 2129.8899 2078.0701 2126.5701 21,000
2063.9800 2098.8999 2063.9800 2086.1399 11,500
2050.0000 2081.6001 2049.1001 2056.3000 14,500
2044.8000 2061.0300 2035.0100 2056.3601 13,900
Weekend
Weekend
2056.7700 2065.3301 2038.1500 2044.9301 22,200
2047.2900 2063.2200 2014.0100 2052.1699 15,900
2052.4399 2066.0000 2034.8500 2039.1899 18,500
2071.3701 2071.3701 2039.9200 2052.4399 17,000
2060.0000 2091.8999 2054.1001 2076.9299 13,000
Weekend
Weekend
2072.0200 2076.3799 2049.6299 2056.6399 8,600
2084.9900 2098.8899 2054.8701 2071.9700 13,400
2050.3501 2085.0000 2040.0000 2073.8501 18,900
2043.2700 2074.0000 2020.0000 2045.4500 14,300
No trading
Weekend
Weekend
2061.6399 2068.0000 2037.9900 2056.3601 17,300
2084.5601 2098.8799 2059.7100 2061.9199 14,200
2056.0601 2081.9299 2052.4900 2076.9600 15,300
2054.6299 2085.7100 2028.9000 2057.9900 15,900
2040.6200 2075.7300 2028.0000 2060.8401 13,900
Weekend
Weekend
2071.7200 2095.7200 2043.5100 2048.4500 16,500
2063.5100 2083.0000 2017.8500 2074.4900 22,700
2040.4301 2068.0601 2010.0000 2059.5400 16,100
12 · 8-K Pre-market · 08:02 ET 8-K ↗
2008.0400 2056.1001 2003.9700 2047.3101 31,200
2036.7600 2072.0000 2032.0000 2062.8601 17,400
Weekend
Weekend
2083.5601 2089.5000 2027.2700 2041.9000 23,300
No trading
2081.9399 2099.4199 2069.1899 2078.0300 14,100
2076.0000 2143.2500 2070.0000 2078.6201 14,200
2069.5300 2081.2900 2057.9299 2075.5300 11,700
11 · SC TO-I/A Pre-market · 06:04 ET SC TO-I/A ↗
Weekend
Weekend
2092.8601 2110.4299 2054.8899 2062.3401 15,800
No trading
2091.0000 2100.0000 2070.9500 2088.0500 7,700
2082.9399 2115.0000 2078.0601 2090.8999 22,400
2026.2000 2097.1299 2015.1000 2083.1399 23,000
10 · SC TO-I/A Pre-market · 08:37 ET SC TO-I/A ↗
Weekend
Weekend
2038.1500 2048.0200 2038.0000 2042.0200 20,500
2062.9399 2098.8000 2036.0000 2040.0000 19,400
2049.6599 2053.1599 2037.6000 2046.6500 21,800
2068.5801 2092.0000 2027.8300 2045.3101 29,700
2059.6201 2072.2200 2051.5000 2068.1699 21,800
Weekend
Weekend
2043.8500 2054.8501 2035.4399 2054.5100 13,700
2057.5901 2127.9700 2032.3000 2044.8700 30,500
2021.4600 2045.5000 2014.6899 2040.9399 23,900
2024.2100 2038.0000 2010.0000 2018.7500 25,400
2033.0000 2097.4900 2013.1100 2013.5200 23,300
9 · 8-K Pre-market · 08:10 ET 8-K ↗
Weekend
Weekend
2026.3000 2046.1801 2019.0000 2034.7900 27,400
2023.0000 2050.8999 2020.0500 2037.7900 17,800
2030.9600 2039.7900 2013.2900 2025.5500 16,700
2025.2000 2041.5000 2022.3000 2027.4100 25,800
2028.2200 2048.7700 2018.2700 2024.8900 15,200
Weekend
Weekend
2030.4399 2042.8900 2023.4500 2024.2500 9,300
No trading
2005.0000 2037.3500 2004.1801 2029.0601 13,500
2000.8400 2030.4000 2000.0000 2003.6500 14,500
1992.8199 2002.3500 1961.0000 1996.9900 24,300
Weekend
Weekend
1959.0000 2013.0500 1959.0000 2000.0000 26,600
8 · SC TO-I Pre-market · 06:03 ET SC TO-I ↗
1901.5500 1913.0000 1875.5000 1881.6100 26,300
1901.3000 1909.8900 1870.0000 1889.3000 20,700
1900.7700 1918.0000 1900.0100 1900.3400 21,000
1931.8900 1943.4600 1900.0000 1900.0000 13,600
Weekend
Weekend
1905.0000 1934.9900 1902.0000 1924.6700 20,100
1929.3800 1941.1300 1911.4200 1915.0900 18,400
1930.5500 1949.8900 1915.4600 1934.4700 16,500
1906.9000 1935.3900 1902.0000 1925.0100 15,800
1905.8000 1921.0500 1899.5800 1901.7600 19,300
Weekend
Weekend
1895.0000 1928.7500 1893.0200 1908.4600 25,100
1901.1000 1923.7400 1888.0000 1892.0200 30,300
7 · 10-Q Pre-market · 09:07 ET 10-Q ↗ 6 · 8-K Pre-market · 08:18 ET 8-K ↗
1897.9600 1925.9000 1894.2400 1897.4200 17,200
1900.2000 1929.2000 1891.8300 1920.6000 28,200
1900.7500 1917.7500 1863.6000 1899.8700 36,700
Weekend
Weekend
1902.4301 1920.0000 1890.0000 1904.5601 27,800
1905.2000 1930.5000 1903.2500 1907.0000 19,300
1914.5400 1914.5400 1897.2300 1897.9900 22,300
1909.0000 1925.0000 1898.9600 1901.3000 29,500
1917.0000 1941.8900 1917.0000 1932.9000 23,600
Weekend
Weekend
1950.0000 1957.6801 1908.5400 1916.1400 26,700
1911.0000 1946.4000 1900.2600 1937.9301 30,200
1916.0000 1927.7300 1900.8199 1902.1899 24,500
1931.6200 1945.0000 1920.9100 1920.9100 17,100
1926.0000 1940.7100 1926.0000 1932.2300 19,100
Weekend
Weekend
1830.1300 1917.3800 1830.1300 1913.2000 32,700
1887.1100 1893.0601 1836.7100 1847.6700 36,100
1931.7900 1939.5000 1890.2900 1892.0100 36,300
1913.5000 1936.5400 1907.0200 1933.0100 23,300
1893.3000 1925.5100 1893.3000 1903.2400 38,300
Weekend
Weekend
1932.6700 1936.0000 1891.2600 1898.0000 21,200
1901.0000 1926.7400 1899.7600 1920.6801 23,100
1900.0000 1905.0000 1892.0000 1896.2000 38,200
1864.0000 1908.6500 1815.4399 1905.2300 39,800
1828.0400 1868.4800 1827.0000 1864.4800 51,500
Weekend
Weekend
5 · 8-K After-hours · 16:20 ET 8-K ↗
1784.7800 1866.2200 1784.7800 1841.3400 88,800
1651.1400 1678.8800 1650.0000 1664.5601 28,800
1670.0000 1670.0000 1648.0000 1650.5000 27,600
1663.7100 1678.8800 1663.7100 1671.5200 33,800
1718.3000 1718.3000 1659.1700 1677.7000 50,400
Weekend
Weekend
1694.9500 1736.0000 1694.9500 1715.9399 32,300
1755.0000 1755.0000 1687.4700 1689.2200 31,200
1759.0000 1783.5000 1755.7000 1756.9900 27,500
1764.1100 1781.0900 1762.6000 1765.5200 38,300
1760.0000 1768.0000 1749.6700 1765.9000 35,500
Weekend
Weekend
1751.3500 1776.2200 1735.0000 1769.8700 45,900
1721.0000 1760.7100 1715.0000 1753.6200 32,900
1724.0000 1728.4800 1711.3900 1722.9800 29,400
1712.7800 1719.4000 1700.0000 1715.5000 29,400
1760.0000 1772.0000 1711.2800 1715.4000 40,400
Weekend
Weekend
1765.0000 1785.7700 1762.8101 1762.8101 26,600
1752.0000 1774.5100 1752.0000 1774.5100 33,600
1779.6801 1790.0000 1752.8800 1760.4800 37,400
1767.1600 1800.0601 1762.7100 1794.6899 82,800
1785.0000 1800.0000 1748.4100 1767.1600 30,900
Weekend
Weekend
1797.6700 1816.0000 1792.0000 1796.0300 20,900
1772.5200 1800.5100 1767.1500 1800.5100 26,900
1795.0000 1819.6899 1763.9200 1772.5200 33,000
4 · 8-K Pre-market · 08:06 ET 8-K ↗
1815.0000 1842.0800 1804.0000 1836.5900 23,800
3 · 8-K Pre-market · 08:19 ET 8-K ↗
No trading
Weekend
Weekend
1837.0000 1839.3101 1830.1801 1830.1801 20,500
1825.0000 1850.0000 1822.0000 1825.3900 25,000
1838.1400 1850.8199 1824.3000 1845.4200 37,200
1810.0000 1836.2100 1810.0000 1835.6899 27,000
1830.0000 1840.0000 1809.9000 1828.0500 24,400
Weekend
Weekend
1856.0000 1868.3600 1848.3700 1863.2200 24,100
1832.3101 1847.3900 1831.0000 1841.4100 20,400
1809.0000 1841.2100 1809.0000 1836.8900 26,000
1777.3800 1813.5300 1777.3800 1813.0900 28,600
1775.0000 1779.0200 1758.6801 1763.4700 32,800
Weekend
Weekend
1838.0000 1848.3101 1762.7100 1769.6000 41,900
1865.0000 1867.4700 1840.0000 1844.3400 30,100
1837.5500 1880.1100 1819.0000 1869.8101 21,900
1786.7900 1828.0300 1779.0000 1824.5900 29,600
1746.0000 1791.1801 1744.0000 1783.5100 37,400
Weekend
Weekend
1759.0000 1789.0000 1750.2100 1751.6200 24,400
1770.1100 1776.9200 1747.6000 1750.3500 49,100
2 · 10-Q Pre-market · 08:28 ET 10-Q ↗ 1 · 8-K Pre-market · 08:03 ET 8-K ↗
1774.9600 1795.4700 1756.0000 1782.7100 32,000
1779.4301 1788.3000 1777.2400 1785.0100 21,200
1777.8700 1790.0000 1774.1500 1774.5000 22,700
Weekend
Weekend
1779.9301 1779.9301 1762.0000 1774.8700 16,900
1790.0000 1796.8000 1780.5699 1787.8000 16,100
1796.0000 1801.0000 1773.2000 1778.7300 15,500
1796.9000 1796.9000 1785.5300 1796.8900 12,100
1780.0000 1789.5601 1780.0000 1789.5601 13,700
Weekend
Weekend
1785.1000 1794.0000 1782.9399 1789.5800 12,100
1785.3900 1785.3900 1777.8800 1777.8800 15,700
1789.1000 1789.1000 1780.5200 1788.2100 13,900
1770.5000 1799.4399 1770.5000 1791.3500 21,000

Announcement Events

Each title opens the filing on the SEC website. Registered users can summarise the filing and up to seven relevant exhibits linked within the same SEC submission.

22 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:17 ET Summarise
21 8-K 8-K (opens SEC filing in a new tab) After-hours · 16:21 ET Summarise
20 8-K 8-K (opens SEC filing in a new tab) Pre-market · 09:02 ET Summarise
19 10-Q 10-Q (opens SEC filing in a new tab) Pre-market · 08:31 ET Summarise
18 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:20 ET Summarise
17 8-K 8-K (opens SEC filing in a new tab) After-hours · 16:21 ET Summarise
16 DEF 14A FORM DEF 14A (opens SEC filing in a new tab) After-hours · 16:00 ET Summarise
15 10-K 10-K (opens SEC filing in a new tab) Pre-market · 09:21 ET Summarise
14 8-K 8-K (opens SEC filing in a new tab) After-hours · 17:19 ET Summarise
13 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:21 ET Summarise
12 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:02 ET Summarise
11 SC TO-I/A SC TO-I/A (opens SEC filing in a new tab) Pre-market · 06:04 ET Summarise
10 SC TO-I/A SC TO-I/A (opens SEC filing in a new tab) Pre-market · 08:37 ET Summarise
9 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:10 ET Summarise
8 SC TO-I SC TO-I (opens SEC filing in a new tab) Pre-market · 06:03 ET Summarise
7 10-Q 10-Q (opens SEC filing in a new tab) Pre-market · 09:07 ET Summarise
6 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:18 ET Summarise
5 8-K 8-K (opens SEC filing in a new tab) After-hours · 16:20 ET Summarise
4 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:06 ET Summarise
3 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:19 ET Summarise
2 10-Q 10-Q (opens SEC filing in a new tab) Pre-market · 08:28 ET Summarise
1 8-K 8-K (opens SEC filing in a new tab) Pre-market · 08:03 ET Summarise