Rolling a call option

I rolled the call option on my position in Silver Wheaton SLW today. In June I had written the August $12.50 call on the stock. Today I bought back the call and sold the Sept $15 call for a net debit of $.90 plus commissions.

The closed position gave a return of 20.35% for 40 days, using today’s closing stock price. The new covered call position will return 4.3% for 53 days if unchanged, about 15% if called away.

I like SLW as a longer term holding, while making some good option premium along the way. They are releasing earnings on Friday, so I am considering buying a put as insurance against any surprises.