By Chuck Mikolajczak

NEW YORK (Reuters) - When FTSE Russell refreshes its indexes after the U.S. stock market close on Friday, shares of hundreds of companies will see an impact as managers adjust their portfolios to reflect new weightings in the widely followed indexes.

In the Russell 2000 small company index, financial firms and consumer staples companies will lose weighting, while materials companies and producer durables will have a stronger role, according to a preliminary analysis of the expected changes by Wall Street analysts.

In the Russell 1000 large capitalization company index, the most notable move is likely to be Apple Inc <AAPL.O>, whose shares could fall further as they are set to lose their weighting and be reclassified as a partial value stock.

Investors have about $850 billion tracking both the Russell 1000 and Russell 2000, according to Nicholas Colas, chief market strategist at the ConvergEx Group in New York, with the majority of that cash pegged to the smaller-cap names.

Roughly 400 stocks will be affected by the announcement, either by being added to an index, removed from one or moving from one index to another, according to analysts' expectations.

FTSE Russell reconstitutes its indexes just once a year.

While some active investors have attempted to jump out in front of the announcement in years past, this year's trades may be condensed to Friday as they wait for the so-called "Brexit" vote to conclude.

"That is going to take front and center, so I assume volume is going to be heavy in the morning around Brexit and the afternoon volume is going to be really heavy due to reconstitution," said Steven DeSanctis, SMIDcap strategist at Jefferies in New York.

Smallcap financial Western Alliance Bancorp <WAL.N> and consumer staples company Casey's General Stores <CASY.O> are expected to move up to the Russell 1000. Western Alliance has fallen 4.2 percent, while Casey's has shed 0.5 percent since Russell announced its preliminary list on June 10.

Materials company Allegheny Technologies <ATI.N>, which is expected to move from the Russell 1000 to the Russell 2000, has gained nearly 6 percent since the preliminary list was published.

It is a "funny quirk" of the rebalancing trades that shares of companies moving up to the large-cap index tend to do worse, while companies moving down tend to rise, said Chad Dale, director of Index and ETF Research at ITG in Toronto. That is because so much more money follows the small-cap index.

Analysts at brokerage ConvergEx Group in New York anticipate the weighting in the small-cap financials <.R2RGSFS> to decline to 26.4 percent from 27.1 percent, while small-cap consumer staples <.R2RGSCS> are expected to drop in weighting from 3.4 percent to 2.8 percent. Credit Suisse expects producer durables to gain a weight of 0.9 percent and materials to gain 0.5 percent.

FTSE Russell did not make any major changes to its methodology this year, though it did tweak the rule about the growing number of companies sporting multiple share classes. Russell will no longer include separate share classes if they cannot meet the inclusion criteria, such as market cap, on a stand-alone basis. The exception is Berkshire Hathaway <BRKa.N>, due to the large spread in price - roughly over $218,000 - between both classes of its shares.

(Reporting by Chuck Mikolajczak; Editing by Linda Stern and Dan Grebler)