The semiconductor index was up 8.70, to 211.52, on Friday and has now gained 11 percent from its 52-week low on Sept. 1 of 190.04.
The Philadelphia Stock Exchange's semiconductor index gained 4.5 percent, to 545.44.
The semiconductor index rose initially and then fell before rising again.
But from January 1, 1997 to April 7, 2000, the semiconductor equipment-maker index gained 1,042 percent.
The Philadelphia Stock Exchange's semiconductor index fell 15.88 points, or 2.7 percent, to 574.30.
The Philadelphia Stock Exchange's semiconductor index dropped 27.49 points, or 4.7 percent, to close at 555.54.
The Philadelphia Stock Exchange's semiconductor index dropped 53.19 points, or 8.6 percent, to 566.51.
The Philadelphia Stock Exchange's semiconductor index rose $27.72, to $564.75.
The Philadelphia Stock Exchange's semiconductor index fell 41.87, to 503.17, a new 52-week low.
The Philadelphia Stock Exchange's semiconductor index rose 3.98 points, to 197.87.