"You and your" vs. "Your and your"

Which is correct, and why?

identifying you and your competitors’ relative market performance

or

identifying your and your competitors’ relative market performance

Each entity is in possession of “relative market performance”, so I think grammar dictates both be your, but it sounds godawful.

It has to be your and your. If you don’t like it, you can say something like ‘...identifying your competitors' relative market performance as well as your own.’

I think that the phrase

your and your competitors’ relative market performance

is a pretty odd fish in the first place—because performance comes out singular here even though the actual subject being discussed is at least two instances of performance (yours and your competitors', the latter of which may be tracked as a set of grouped and averaged numbers or as multiple sets of individual numbers, one for each competitor) considered relative to each other.

In the more normal case, the noun at the end of the phrase would be plural, as in

your and your girlfriend's fathers

and most people (I suspect) would feel absolutely no temptation to express that relationship as

you and your girlfriend's fathers

or

your and your girlfriend's father

or

you and your girlfriend's father

So the real culprit here is "relative performance," which invites us to understand it as referring to one performance that both you and your competitors share, rather than as referring to two (or more) sets of performance data matched against one another. The expression is idiomatically legitimate—indeed, completely normal—but that doesn't make it any less of an impediment to recognizing the real-world comparison that underlies the expression in this instance.

Even in that case, however, any inclination to choose against the replicated possessive in "your and your competitors'" recedes if we recast the conversation as being about matching our performance and our competitors' performance. Would anyone argue in favor of

identifying us and our competitors’ relative market performance

as against

identifying our and our competitors’ relative market performance

? I wouldn't. That the wording is "your and your competitors'" instead of "our and our competitors'" is of no syntactical importance to whether the first word should take the form of a possessive.

I can't think of any plausible argument for adopting the wording "you and your competitor's market performance" or "us and our competitor's market performance" in preference to "your and your competitor's market performance" or "our and our competitor's market performance."

Most of the difficulty here is that the choice isn’t between ‘your and your… ’… it’s between ‘your and your competitors’…

Beyond that, try treating it like the hoary-old ‘I or me…’ and simplify it by dropping one of the parties.

Does ‘… your (relative) market performance’ by itself seem correct?

Does ‘… your competitors’ (relative) market performance’ by itself seem correct?

If they really seem too ugly when you put them back together, slip in a comma to change the impact…

‘… your, and your competitors’…’