I assume those comments are addressed to me. In this forum, it is difficult to tell unless either you quote

__part of__ the posting that you are responding to, or you write something like

@joeu2004 .

First, note that "no guess" is a

__default guess of 10%__, not zero.

I do not believe there is a single guess that "works" for all situations, especially for Excel XIRR.

(See my comments about XIRR unreliable in posting #18.)

And note that sometimes there are multiple IRRs for the same cash flow model. Which IRR is the "correct" one?

Some people expect a negative IRR when the sum of the cash flows is negative, and a positive IRR when the sum is positive.

But as appealing as that might seem, it is based on a fallacy.

Consider a loan of $100,000 with 12 payments of $8900. In this case, we can use Excel RATE to calculate the IRR. But I'll stick with Excel IRR to avoid confusion.

The cash flows can be either {

**-100000**,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900}

or {100000,

**-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900**}.

Arguably, it depends on your point of view: lender or borrower. But actually, the choice of signs is arbitrary, as long as inflows and outflows have opposite signs.

SUM(

**-100000**,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900) returns 6800.

SUM(100000,

**-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900**) returns

**-6800**.

So perhaps you would expect the IRRs to have opposite signs.

But in fact, both IRR({

**-100000**,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900,8900})

and IRR({100000,

**-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900,-8900**}) return the

__same sign__.

(In this case, their values differ in the last decimal place.)

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PS.... For your 3 examples, the following seems to work.

=XIRR(values, dates, IF(SUM(values)<0, -10%, 10%))

As I said, that is based on a fallacy. And it is not a panacea, since even those guesses do not work in all cases.

Perhaps you will get lucky, and that works for all of your projects.