Today marks the debut of an updated version of The Post-Gazette/Bloomberg Index, 60 stocks that reflect the changing nature of the public companies playing a vital role in the region's economy.

The revised list reflects the departure of companies such as Nova Chemicals, sold this summer to Middle Eastern investors, and the emergence of others such as Toshiba [ticker: TOSBF], the majority owner of Westinghouse Electric, one of the region's fastest-growing companies. Not all of the companies are based here -- or even in the United States. But all of them have substantial operations in the region, making the index a proxy for Western Pennsylvania's economy.

Market capitalization (share price multiplied by the number of shares) of the 60 companies ranges from $91 billion for Verizon Communications [VZ] to $33 million for WVS Financial [WVFC], the parent of West View Savings.

The PG/Bloomberg Index consists of one share of each of the 60 companies. It is a price-weighted index, meaning higher-priced stocks are given more weight in the index than lower-priced stocks. For example, Siemens AG [SI], which closed Friday at $79.48, currently accounts for about 5 percent of the index while Indiana County energy services firm Superior Well Services [SWSI], which finished at $6.53 Friday, makes up only 0.4 percent.

Weighting the members by price makes the index different than the Standard & Poor's 500, a broad indicator of Wall Street's condition. The S&P 500 is a capitalization-weighted index, meaning companies with larger market values account for more of the index's value than stocks with smaller market capitalizations.

Members of the PG/Bloomberg index include several companies which trace their roots to Western Pennsylvania's Industrial Revolution: U.S. Steel [X], PPG Industries [PPG], H.J. Heinz [HNZ] and Alcoa [AA]. The index also includes the region's major players in energy, such as Consol Energy [CNX], CNX Gas [CXG] and EQT [EQT], the company formerly known as Equitable Resources.

The region's health care sector is represented by Mylan [MYL], the world's third largest generic drug company, McKesson [MCK] and Koninklijke Philips Electronics [PHG], the owner of medical equipment maker Respironics. Retail sector members are American Eagle Outfitters [AEO] and Dick's Sporting Goods [DKS].

Banks account for 20 percent of the index. The dozen appearing on the list include PNC Financial Services Group [PNC], Bank of New York Mellon [BK] and other long-established financial institutions. There's also a new entry: First Niagara Financial Group [FNFG], the Buffalo bank purchasing 57 former National City branches federal regulators directed PNC to divest when it acquired the ailing Cleveland bank last year.

Metals producers make up another 10 percent, including one new member: Horsehead Holding [ZINC]. The Monaca zinc producer is the top-performing stock in the index this year, advancing 127 percent through Friday.

In addition to Toshiba, three other companies with units spun out of Westinghouse are in the index: Curtiss-Wright [CW], which purchased Westinghouse's government services business in Cheswick; Eaton [ETN], which merged Westinghouse's electrical distribution and control business with its Cutler-Hammer unit; and Emerson Electric [EMR], the operator of Westinghouse's former process controls business in O'Hara.

The PG/Bloomberg Index severely underperformed the S&P 500 and the Dow Jones Industrials this year, generating annualized returns of 1 percent through Friday vs. gains of 20 percent for the S&P 500 and 12 percent for the Dow.

Of the regional index's 10 worst performers this year, seven are banks. They are First Niagara, PNC, Parkvale Financial [PVSA], WesBanco [WSBC], FNB Corp. [FNB] and the two Indiana banks that turned in the weakest performances among index members: First Commonwealth Financial [FCF], down 46 percent for the year, and S&T Bancorp [STBA], down 61 percent for the year.

The regional index also took it harder on the chin than the major market indexes in last year's market mayhem, generating negative returns of 40.5 percent in 2008.

Longer term, the PG/Bloomberg index's track record looks a little better. Over the 10-year period ending June 30, it generated annualized returns of 3 percent vs. negative returns of 0.4 percent for the Dow and 2 percent for the S&P 500.