By Jud Pyle, CFA, chief investment strategist for the Options News NetworkVarian Medical Systems ( VAR - Get Report) has rallied more than 5% today as the rumor mills churn about a possible buyout. Siemens ( SI), a German technology firm, is speculated to be the potential suitor. Soleil Securities initiated coverage on the stock today, giving VAR a buy rating and a 12-month price target of $38. Call buyers have swooped in as a likely result of this speculation. The April 35 call has seen more than 5,000 contracts trade on paltry open interest of fewer than 600 contracts. Even with today's gain in the stock, this call is still out of the money, with about one week until expiration.