I remember reading somewhere that paying off your house is a bad idea. A 10 year mutual fund would more than cover the intrest incurred on your house right? After you write off the interest on taxes?
There are a few things to consider here.
First, writing off interest on your taxes is only useful if your itemized deductions are greater than your standard deduction. And then it's only useful above your standard deduction. Second, there is no guarantee about the stock market, 10 years in general is long enough to see decent returns, but 1998 to 2008 would have netted you basically nothing or worse.
Because I have nothing to do this evening I'll do a quick case study.
Let's take a household income of $60,000, a family filing their taxes jointly, and a house worth $200,000 and a balance of $180,000 at 5% for 30 years (which would be a $966.28 payment). That means that in the first year they will pay about $9000 in interest. Let's say they are also good Christian folks who tithe 10% of their gross income, so $6000. So they have $9000+$6000=$15000 in itemizable tax deductions.
The standard deduction for married filling jointly is $11,400, so since $15,000 is greater they would want to itemize. So by going the itemized route they reduced they taxable income by $3600 (the difference between the itemized amount and the standard deduction). And at the marginal tax rate of 15% they saved .15*3600=$540 that year in taxes. $324 from mortgage interest, $216 from their charitable donations.
Now lets say that that they had an extra $100 a month that they could either invest in the stock market, or use to pay down their house.
So for the sake of simplicity let's say that their income stays the same, and tax rates and whatnot stay the same for 10 years.
Over those 10 years they would have saved a grand total of $2856.80 off of their taxes due to itemizing their mortgage interest (that number only is the mortgage portion, not the charitable donation portion). For the sake of simplicity we'll assume that the yearly tax savings were added equally to each $100/month investments. That comes out to $126/month the first year, $125/month the second year, down to $114/month the 10 year. So if they put that money each month into the stock market they will have $x after 10 years (we'll compute x for various scenarios later). The remaining balance on the house is $146,415.72 and they paid a total of $82369.19 in interest.
So let's say that instead of using that $100 to invest in the stock market, they put that as an extra payment to the house each month. Furthermore their yearly tax savings due to itemizing will be put towards an additional lump payment to the mortgage each year. At the end of 10 years the balance on the home would be $128,231.22 and they paid a total of $78164.55 in interest. And of course they would have $0 in their stock market investment because they put that money towards the mortgage instead.
So back to the stock market scenario. Again for simplicity (and it's getting late and I don't feel like finding monthly data) I'll use
this to calculate various 10 year period's returns.
2001-2010: 1.31% yearly
1999-2008: -1.47% yearly
1995-2004: 12.12% yearly
1991-2000: 17.59% yearly
So using those numbers you would the following balance in your account.
2001-2010: $15,573.97
1999-2008: $13,331.79
1995-2004: $28,937.04
1991-2000: $39,792.56
Recall that the stock market route has a mortgage balance of $146,415.72 and the other route has a balance of $128,231.22. A difference of $18,184.50. So in the 2001-2010 and the 1999-2008 you would be further ahead paying down your mortgage. In the 1995-2004 and 1991-200 you'd be further ahead doing the stock market.
However there's more to it than that. Let's say at the end of 10 years you were laid off and your income went to $0, but thankfully you found a great job offer in the state over, but you need to move. Now if home value stayed at your original $200k or went up you'd be fine selling and moving. But let's say the housing market tanked, and your home is now worth $130k. So you are underwater by $16415 in the first scenario, ahead by $1769 in the second.
If this all happened in the 2001-2010 or 1999-2008 period your stock market account would not be enough to cover the difference in your house and would have to scrounge up the difference (personal loan, short sale, or something) to get out from under your house. In the other scenario you would be able to leave with $1770 in your pocket.
In the 1995-2004 or 1991-2000 years you'd be just fine.
The point is there is risk associated with your mortgage (ie, what happens if I lose my ability to pay it? What happens if the value goes down?) and there is risk associated with the stock market (will I have a positive return over this time period?). The risk associated with your mortgage is greatly reduced by paying it down (lower likelihood of being stuck underwater) and you are guaranteed a rate of return roughly equal to your mortgage interest rate (5% in this case) on that extra $100/month.
Furthermore, there are plenty of scenarios where there is no tax advantage to itemizing your mortgage interest (ie, when your itemized deductions are lower than your standard deduction). In that case paying down your mortgage is an even better idea.
So anyway, sorry about this wall of text. I had nothing better to do. Oh, and I'm sure I fudged some numbers somewhere, so I apologize in advance.
edit:
tl:dr, see Engineer's post below mine