Analysts who are literally in the "twilight" i.e. on a downward slope.

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Note added at 21 mins (2005-01-29 20:20:30 GMT)
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After additional thought, in this context the best fit would be:

Even analysts whose own stars have faded...

I base the suggestion on the second part of the sentence "... Gewinn- erwartungen ... festgehalten". So they obviously expected some development and on the basis of this development made some recommendations, which people found reason to doubt. But these analysts stick to their guns ... no change in expectations (and recommendations).
A bit more context would have been useful!

all of my collegues propose terms having the meaning "analyst lost their credibility", but could its meaning represent "skeptical/suspicious" within this context?

Even those analysts, on whose forecast of profits for 2002-2003 doubts have been cast, continue to cling to their predictions for the most part.
Alternately: whose forecasts have been clouded by doubt
The point is:
The analysts are neither discredited nor have them come under suspicion (it is not a court case!), it is simply their forecasts that have "entered the twilight zone". The German wording is somewhat imprecise but quite intelligible for any informed reader.

German term (edited): ins Zwielicht geratenen

I am SURE that there's another, shorter and better way of expressing that in English - but I believe that's basically what it means here.

"Abilities" may be replaced by another word, depending on context (I just hid my previous answer where I used the word "reputation", but that wouldn't have fit the context at all)

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Note added at 27 mins (2005-01-29 20:26:29 GMT)
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I just googled for the words \"Zwielicht\" and \"suspicion\", and found this:

http://www.edward-norton.org/fear.html :
\"In Germany, the film is called \"Zwielicht\", which directly translates to \"twilight\" or if phrased as ins zwielicht geraten, it means \"to lay oneself open to suspicion\".\"

Which suggests using \"who have laid themselves open to suspicion\".

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Note added at 15 hrs 23 mins (2005-01-30 11:22:30 GMT)
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... another suggestion: whose abilities have come to be viewed with suspicion.

reputation as having done something bad in the past. How about entered the grey zone?

Shares, or stocks, frequently "take a beating" on the stock market, so why not the reputations of the analysts.

I don't know, however whether the writer means a certain group of analysis "analysts whose reputation"
or analysts as a whole "analysts, whose reputation"