GENERAL MOTORS CORP.'S bankruptcy will ripple across business. Here's a look at who gets hit, and how:

Investors

They will be the biggest losers dollar-wise. Just how badly they fare depends on whether their money is in stocks or bonds.

Bondholders will come out slightly better. Left with little choice as a GM bankruptcy appeared imminent last week, a majority agreed to a forgive $27 billion in debt and promised not to challenge the reorganization in court in exchange for equity in the new company. Bondholders would get 10% of GM's shares, and warrants allowing them to boost that to more than 20%. This deal was less appealing to smaller bondholders, many of whom invested in GM to receive interest to sustain themselves in retirement.

For shareholders, the picture is bleaker. Even without a bankruptcy, GM's plan would have left them with just 1% of equity. In bankruptcy, they will be wiped out. GM's stock price, last trading under $1, doesn't have much further to fall. Nine years ago, GM shares were trading at more than $90.

United Auto Workers

The auto workers union faces the bankruptcy with backing from the company and the government.

A bankruptcy judge could void the union's modified labor deal with GM, but that is unlikely. The union is likely to be treated like a preferred creditor to GM. Unlike some holdout bondholders, the UAW could be painted as a partner in the process to reduce labor costs rather than an obstacle to orderly reorganization.

Post-bankruptcy, the UAW, the richest union in the country as measured by assets, will be in solid financial shape, with its base wages and retiree health-care benefits largely untouched and a large equity stake in GM via a union-controlled trust. But many workers see future job and benefit cuts as inevitable. As part of the deal, the UAW agreed not to strike until 2015.

GM wants to increase imports of small cars it makes in low-wage countries such as South Korea and, for the first time, China, which the union had strenuously opposed. The UAW was able to get GM to pledge that it will invest in an unnamed idled U.S. plant and accompanying stamping facility to make compact and small cars not currently built at any other U.S. site. The plant would be outfitted for assembling as many as 160,000 cars a year.

Competitors

The bankruptcy of the nation's biggest car maker offers a short-term opportunity for rivals to gain market share, but some analysts say a restructured and recapitalized GM with government backing could have an unfair edge.

Cross-town rival Ford Motor Co., for instance, the only domestic auto maker to avert a government bailout, has gained market share this year, as that of GM and Chrysler fell, and is expected to continue to fare well. The Dearborn, Mich., company has been aggressively restructuring, slashing its debt load, lowering labor costs and raising $1.4 billion in an equity sale.

But after GM emerges from bankruptcy with a substantially reduced debt and cost base, Ford still will need to rely on the markets for capital. The biggest issue for Ford "is the debt service," said David Cole, chairman of the Center for Automotive Research in Ann Arbor, Mich. "They can't avoid the debt that they have. Sometimes when you escape the hangman's noose, you can still get shot on the battlefield."

Meanwhile, GM's chief foreign rival, Toyota Motor Corp., is flagging. Toyota reported its first annual loss in 59 years, and awaits a management shake-up at its June shareholder meeting, which will usher in new president Akio Toyoda. Toyota has lost out to companies such as Hyundai Motor Co. that have seized on the struggles of U.S. auto makers to build brand recognition and grab customers.

Dealers

Car dealers have been slammed by the plunge in sales over the past year, and GM's bankruptcy won't make things any easier. "The confidence level is just so weak it keeps pulling us back," said John Bergstrom, chairman and chief executive of Bergstrom Automotive in Wisconsin.

In the past year, more than 1,300 dealers have been forced out of the market as the credit crisis deepened and consumer confidence sank. Chrysler and GM cuts have cost an additional 1,900 dealers their franchises.

Even survivors have to contend with tough credit markets and rising unemployment. They also must fend off "irrational pricing behavior" caused by dealers who are closing shop and selling their inventory at bargain prices, said Richard Kwas, an analyst at Wachovia Capital Markets.

In the long run, surviving dealers should be able to enjoy higher sales and less competition. The sooner the bankruptcy process proceeds, the sooner consumers may return, say dealers. Many are scouting opportunities to acquire more brands and locations, as weaker dealers throw in the towel.

Suppliers

Parts makers reliant on GM already are struggling with lower volumes, tight credit and rolling production shutdowns that reduce demand for parts. Bankruptcy will only deepen the troubles.

GM likely will ask the court to allow it to keep paying key vendors in order to maintain its supply of parts. That will be a relief for suppliers that make the list. It means they are likely to recover at least some of the money they are owed and will continue to do some business with a new GM.

But only if they survive the summer. GM last paid its suppliers at the end of May. With production down and a bankruptcy judge in control of the company, it could be a long time until suppliers see their next check. Analysts say those with balance sheets strong enough to stay afloat until production resumes could benefit from a bankruptcy that hastens the demise of rivals.

Companies already short on cash, such as Lear Corp. and American Axle & Manufacturing Inc., are on shaky ground. GM accounted for 23% of Lear's 2008 sales and 74% of American Axle's. Metaldyne Corp. and Visteon Corp. already have filed for bankruptcy protection, along with smaller suppliers Contech LLC and Hayes Lemmerz International Inc.

Their loss could be a gain for stronger suppliers such as Magna International Inc. and Johnson Controls Inc. It's possible struggling suppliers will get indirect help from the government through GM in the form of a more payments to suppliers than might be the case in a traditional bankruptcy. A person familiar with the Treasury Department's discussions expects more suppliers to file for Chapter 11 and said, "We will support GM — and Chrysler for that matter — in trying to make it orderly."

Write to Kate Linebaugh at kate.linebaugh@wsj.com, Matthew Dolan, at matthew.dolan@wsj.com, Sharon Terlep at sharon.terlep@dowjones.com and Andrew Grossman at andrew.grossman@wsj.com