The wife may be privy to the banks customers activities, and the husband must be considered privy to all the same, simply by proximity regardless of her honesty or intent.

The wife may have knowledge about $bigco buying or selling $bigthing, and the husband may gain that same knowledge from her, even if she's honest and never intentionally disclosed it. (people aren't perfect and clues can slip, or he simply has access to her laptop or that scratch pad where she wrote down the essentials of a phone call etc.

I worked at a publicly traded company where everyone internal had knowledge of product releases with Apple. It was a trading frenzy with open discussion of trading decisions that predictably paid off. I remember it distinctly because it was right after company-wide training on insider trading with talks of prison time etc before our discounted stock grants. All it did was teach people how to conduct insider trading. The training was considered all that was needed for compliance. Zero enforcement, insider trading is the default. Humans cannot resist.

While I don't know the specifics, product releases tend to have a whole lot less to do with stock movement than the details of financial performance. And during much of the last couple of decades it has been pretty hard for investments in Apple not to pay off.

Product release from a ragged-arse of a company that had no prior dealings with Apple nor any public information about a coming product with Apple? Insider trading. It's a fine line that most can easily convince themselves to cross.

She has access to every and any database as she is the one who pulls the data for auditors, so is privileged to confidential and/or non-public knowledge. And like someone mentioned above, just by proximity, I (potentially) have access to that knowledge.

She would almost certainly have early knowledge of irregularities at her own company but potentially more broadly in the sector because people talk. Trading restrictions don't really cost an employer anything so they often figure that it's easier to get rid of even the possible appearance of impropriety even if it costs some employees/their spouses money.

At the most basic level, I worked for a company that wouldn't let you sell company stock, even as a non-executive, during a window around earnings being reported.

Timing buys/sells before during investigations, early access to judgements, pre-IPO info... your basic insider trading.

An example that comes to mind would be overlooking something during an audit in exchange for a kickback.

Trade on insider information.