Ford Motor Co.'s emergence as Detroit's darling may have fueled jealousy at General Motors Co. headquarters, but the archrival's rising shares could help GM as it readies its landmark return to public markets, Reuters reported.

As GM's only major U.S.-listed rival, Ford is the company investors and bankers are turning to as they debate the largest U.S. automaker's theoretical value ahead of the high stakes IPO scheduled for soon after next week's U.S. mid-term elections.

There are several ways to calculate value for GM, including using a multiple of its projected cash flow based on Ford's multiples, or doing an implied value calculation based on where GM bonds are trading.

Initially, GM's IPO -- just over a year after the automaker's bankruptcy -- was widely expected to weigh on Ford's shares, which have appreciated sharply since hitting a record $1.02 low in November 2008 and were trading around $12 when news of GM's stock float first began to circulate in May.

Ford executives were repeatedly asked to assess the risk that mutual funds and other institutional shareholders might "rebalance" their portfolios, dumping Ford stock and buying GM.

"Just mathematically, a lot of mutual funds and other investment entities will probably spread their investment out over the sector more," Ford Executive Chairman Bill Ford told reporters in August, two days after GM filed the initial paperwork for its IPO with the U.S. Securities and Exchange Commission.

Whether GM benefits -- and Ford suffers -- from investors diversifying their autos holdings will not be determined until after GM's debut in mid-November. But in the meantime, Ford's share rally and a broad rebound in auto industry stocks across the board are helping GM's valuation.

Ford, which posted losses totaling $30 billion from 2006 through 2008, has emerged as the strongest of Detroit's "Big 3" automakers under a turnaround plan led by CEO Alan Mulally.

Its stock hit a six-month high of $14.47 on Tuesday when it impressed investors with a $1.7 billion profit for the third quarter.