...you think all of page 3 will be admissible going to his character? Or hearsay? I mean, I guess he probably wouldn't testify himself. How many jobs do you have to resign from for bad behavior before no one will hire you and you have to start your own company? Apparently at least 3.
The rules of evidence are complicated and vary by jurisdiction but here are some general propositions, which are relayed with the understanding that the rules may have exceptions in a given jurisdiction and therefore my brief summary should not be relied on:
Evidence that the accused is the sort of "bad person" likely to commit the crime charged is not relevant or admissible in a criminal proceeding, unless the defendant first offers evidence that he is a good person (whether through testifying himself or otherwise). If the defendant offers evidence that he is a good person, then the prosecution is permitted to rebut that. In general though, the fact that the defendant has been fired from a series of jobs is not relevant unless those facts are otherwise relevant to the trial (for example, the fact that defendant has a history of unsuccessfully working in the industry might be relevant to his motive). Note that motive is not an element of the offense, but it can still often be relevant.
If the defendant testifies, then the prosecution is permitted to ask questions whose answers would tend to suggest that the defendant's testimony should not be believed because the defendant is not credible. Evidence of general "bad character" is irrelevant; it is only admissible for impeachment to the extent that the evidence would suggest that he would tend to lie under oath. Evidence that he has been fired from several jobs is probably irrelevant even if he does testify, unless he was fired for reasons that have to do with dishonesty (and the Fidelity resignation might arguably relate to that, since the allegations in the Maryland securities proceeding say he was "not forthcoming" about the facts that led to his termination).
Evidence of past criminal convictions or regulatory sanctions are only relevant to the extent that either (1) they are proof of the underlying facts of those proceedings (in other words, the facts of the prior bad acts are themselves relevant to the current case), or (2) they suggest that the defendant is dishonest. However, because of the difficulty of determining whether a criminal conviction is relevant, most jurisdictions have general rules. For example, in the general rule in most US states is that evidence of past felonies are admissible to impugn credibility (but not to suggest that defendant probably committed the crime charged).
All potential evidence is subject to exclusion if the prejudicial value of admitting the evidence would outweigh the probative value.
There's no hearsay issue with the evidence of the terminations because (if admissible) the prosecution could call evidence from people who worked at those past employers to testify to the relevant facts.
Subject to a statute that says otherwise, the general rule for regulatory proceedings like the one discussed in OP is that the rules of evidence do not apply at all, and that any evidence whatsoever can be admitted, so long as the regulator considers it helpful.
Again, the rules do vary by jurisdiction, and this is just an attempt to state some general principles, but I don't know anything about specifically Maryland evidence law.