Marconi and Carlton are among companies facing relegation from the FTSE 100 index.
They're expected to bow out in the list of leading shares' quarterly reshuffle.
Today's share prices will decide whether they are in or out, though the changes to the index will not take effect until later this month.
They are expected to be replaced by companies from the "old economy" in a move which some analysts believe could reduce the index volatility.
Other companies likely to be ditched from the FSTE 100 include software group Misys, computer services firm CMG, publisher United Business Media and Telewest.
The FTSE reshuffle will come during a week of tension before a key interest rate decision by the European Central Bank.
The rate decision on Thursday is expected to take into account statistics on several eurozone countries' gross domestic product during April, May and June this year.
The GDP statistics are expected to reveal some of Europe's largest economies, including Germany, are close to suffering recessions.