By Prince McLean

Published: 09:00 AM EST

In its second report on the subject in as many days, investment bank PiperJaffray estimates that Apple will earn an incremental 27 cents per share for every half-percent of additional market share registered by its Mac computer line in 2007.

Earlier in the week, the financial firm reported that the Mac maker posted a 2.6 percent global share for the three-month period ending March, up from 2.5 percent during the December quarter and from 2.1 percent during the year-ago quarter.

"Street estimates currently assume Mac market share of 2.7 percent for 2007," analyst Gene Munster wrote in a followup report on Tuesday. "In our estimation, an increase in Mac market share to 3.5 percent for the year would lead to upside to Street 2007 earnings-per-share of $0.44 or 12.3 percent."

The analyst's market share sensitivity analysis mapped out successive scenarios. For example, if the Mac were able to secure a 4.0 percent share for 2007, per-share earnings would increase by $0.71. That figure would balloon to $1.24 should the Mac account for just 5 percent of PCs sold globally throughout the year.

"Strong Mac sales in Apple's March quarter enabled the company to gain share despite stronger than normal PC sales," Munster told clients. "With Apple heading into three quarters of significant product releases (iPhone, Leopard, new iPod) and the education buying season, we expect year-over-year market share gains to continue."



The PiperJaffray analyst noted that in over two years, the only quarter in which Macs saw a year-over-year market share decline was the first quarter of 2006, during the heart of the Intel transition.

"Apple announced the transition to Intel processors in June 2005, but did not ship the first Intel Macs until late January of 2005," he wrote. "And only the final quarter of the period between the announcement and the products shipping, calendar Q1'06, saw a year-over-year decline in Mac market share."

Munster maintains an "Outperform" rating on shares of Apple with a price target of $140 per share.