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The S&P 500 index added 8.3% in October, a welcome return to the upside following a dip in August that left the index down about 7.5% for the third quarter.  The index is now up slightly since the beginning of July, but up just 1% year-to-date.

In October, six stocks posted gains of more than 30% to lead the index to the monthly gain. The top two gainers both announced in October that they are being acquired.

6. TripAdvisor Inc. (NASDAQ: TRIP) posted a monthly gain of 30.6% and closed October up 3.5% Friday at $83.78. The stock’s 52-week range is $62.24 to $94.00 and the high was posted in late July. The stock soared on October 13th with the announcement of a strategic partnership between TripAdvisor and Priceline.com. The consensus price target on the stock is $83.91.

5. E. I. du Pont de Nemours and Company (NYSE: DD) added 35.3% to its share price during October. The stock closed Friday at $63.40, up less than 1% for the day, in a 52-week range of $47.11 to $80.65. Former CEO Ellen Kullman resigned early in the month and investors apparently approved. The stock’s 52-week high is $80.65 and was posted in mid-March. The consensus price target is $62.83.

4. First Solar Inc. (NASDAQ: FSLR) stock added 33.7% to its share price in October with a pop of nearly 12% on Friday to close the week at $57.07 in a 52-week range of $39.18 to $65.50. The solar energy company reported better-than-expected quarterly results on Thursday, helped by a major asset sale. The consensus price target on the stock is $64.06.

3. Wynn Resorts Ltd. (NASDAQ: WYNN) posted a monthly gain of 35.27%, the largest part of which came following an announcement by the Chinese government that it would take its thumb off the scale (a little) regarding tourism to the gambling resorts of Macau. Shares closed up less than 1% on Friday at $69.95 in a 52-week range of $50.96 to $191.73. The consensus price target on the stock is $85.06.

2. KLA-Tencor Corp. (NASDAQ: KLAC) shares rose 35.32% in October with most of the bang following the announcement on October 13th that the company was being acquired by Lam Research for north of $10 billion. The stock’s 52-week range is $44.95 to $84.21 and the high was posted way back in November 2014. The consensus price target on the stock is $65.75, a bit shy of the $67.02 per share offer from Lam.
1. SanDisk Corp. (NASDAQ: SNDK) is another company that announced that it will be acquired, in this case by Western Digital. The announcement shoved the disk drive maker into its position of October’s third worst performing stock, but did wonders for SanDisk. Shares closed Friday at $77.00 in a 52-week range of $44.28 to $106.64. Western Digital’s offer is a mix of cash and debt that values SanDisk at $86.50 per share (about $19 billion).

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