“One of the major reasons that Apple’s shares have declined from $609 the day of October’s earnings announcement to $527 was the company’s gross margin of 40.0% in the September quarter and its guidance of 36.0% for the December quarter,” Chuck Jones writes for Forbes. “These compare to 44.7% in the December 2011 quarter and 47.4% at its height in the March 2012 quarter.”

“One of the major reasons for the 36% gross margin guidance is due to about 80% of the products Apple is shipping in the quarter being new (iPhone 5, iPad 4, iPad mini, new Macs and new iPods),” Jones writes. “This means the company’s component suppliers and manufacturers are at the lowest production yields and therefore highest costs.”

Jones writes, “For the December 2012 quarter I am estimating total revenue of $57 billion (vs. guidance of $52 billion and the Street at $54.4 billion) with iPhone sales of 50.5 million units, $32.6 billion in revenue and 57% of total revenue. While there are higher costs associated as mentioned with all the new products and especially the iPad Mini whose sales have been very strong (which probably has lower gross margins than the iPad) I believe total gross margins in the December quarter could approach if not be higher than 40%.”

Find out how Jones arrives at his gross margin estimate in the full article here.