Calls lock in the price where investors can buy shares, so they can generate some nice leverage in the event of a rally. They can also predict moves in the share price because large traders often amass calls before building a position in a stock.
That happened yesterday as Juniper shares traded for about $16.90 when the calls hit. Buyers stepped in later in the session, driving shares up 1.67 percent to $17.09 even as the broader market fell in the afternoon. At the same time, the December 17 calls inflated by more than 10 percent to $0.70.
Overall option volume in the maker of telecom gear was quadruple its daily average. Calls accounted for more than 80 percent of the total, a reflection of the bullish sentiment.
—By CNBC Contributor David Russell
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David Russell is a reporter and writer for OptionMonster. Russell has no positions in JNPR.