The frantic price swings last week in stocks like GameStop and AMC Entertainment, led by retail traders aiming to take on Wall Street, have spread to a new target: silver. The price of the precious metal jumped 10 percent on Monday to the highest in eight years after online calls to create a “silver squeeze.” The attraction to silver came as the S&P 500 index rose in early trading, following gains on European and Asian stock markets. Retail websites for buying silver coins and bars said they were experiencing high demand and there would be delays in shipping orders.