Ok, taking your points in order:
Bonds: yes. Lots of them. Don't be scared of bonds. Bonds are your friends, providing you can get them at a reasonable interest rate. In general I will rack up the full $10 million worth of bonds as soon as I can, and keep them for the entire game.
I know this is contradictory to some advice you may have seen elsewhere, but it's a great way to get things humming. Usually, I will draw the line at 12% interest for any single bond, and even that is pushing it. I prefer to keep the
average interest rate under 10%. Any industry I build should generate a profit of 20% of build cost per annum, which means the bonds are making me a profit even after I pay the interest.
Given how the credit ratings and economy cycles go in the game, what happens in rough terms is that I'll spend the first few years gradually upping the number of bonds. I'll stop when the interest rate starts climbing too high, and wait a little for better terms. I'll use the cash to build strategic industries and/or connections, carefully chosen to generate lotsa moolah. Once I'm in a good position and the economy is booming, I'll have an AAA credit rating so I'll refinance all bonds at the minimum of 5%. After that, I ignore them.
They're just money in the bank from then on, because everything I have used to them to pay for is making me way more than 5%, so repaying the debt would actually cause profits to drop. It's better to keep paying the 5% on the bonds and use your capital for expansion, because anything you build with the money will make
at least 10%, so that will generate greater profit.
Short version: as long as the stuff you build with the money can make more than the interest rate you pay on your bonds, you are better off NOT repaying bonds. At all.
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I think people get game finances a bit confused with household finances. It's not like a home mortgage. With a mortgage, you're usually paying an interest rate that means the payments are a fairly nasty chunk of your income, and your income is fixed. Added to that is the security aspect, in that once you own the house you're out of potential trouble with creditors. There's the possibility of foreclosure, or of losing your income, or of it reducing, due to circumstances. Obviously, you'd like to get rid of the debt ASAP. Makes sense.
Game finance is different, because you are not on a fixed income, and the creditors will never call you out. These are critical differences. You can rack up as much debt as you like, as long as it's profitable, and use it to constantly expand your income.
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Some people say that repaying bonds increases your company book value. It doesn't. In fact, the initial result of repaying a bond is a
decrease in CBV. Why?
If you repay a bond, your company cash decreases by $510k (bond's nominal value + 2% early repayment fee). Since CBV is company cash + company assets - company debt, decreasing company cash by $510k means your CBV drops by $510k. Your debt also decreases, but only by an even $500k. So, the initial result of repaying a bond is that your CBV decreases by $10k.
Of course, the argument will be that this is only the initial result, and the lack of interest payments means your CBV will soon catch up and start looking better. That brings me back to what I said earlier:
the stuff you build with the capital will make you more.
Say you're in the middle of the game. Your company is looking solid and the economy is booming. You have a good credit rating (A or higher) so the most you should be paying on any bond is 7%. You think "Hey I can pay off some debt and make my company stronger". You take $1 million worth of company cash and pay off two bonds. Congratulations. This will save you (at 7%) $70k per year.
If you don't repay the bonds, and use that money to build yourself something tasty that generates a 20% return, that's going to bring in $200k per year. Subtract the $70k interest you'll still have to pay and you're $130k ahead. Every year. Compounding. That means after eight years you are far enough ahead to have an extra million of cash available for expansion/dividends/whatever.
This is money that would have been lost to you if you had repaid the bonds, because you wouldn't have been able to use the capital to build the profitable industry or whatever. So, over a period of eight years,
repaying those two bonds would have cost you $1 million.
Extrapolate that to the full 20 bond/$10 million limit and it's fair to say that, as long as you are playing the game the right way, holding $10 million of debt in bonds will increase your company profits by $1 million per year.
That might be a surprise to some people, but it's true.
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PS: Refinancing bonds. Taking out a bond incurs a 2% fee, and repaying a bond early also incurs a 2% fee. So, if you refinance an existing 9% bond in favour of a new 5% bond, it will break even after 1 year. After that, it's making you more. If you refinance a 9% bond at 8%, it will take four years to break even. Usually I wont bother refinancing until I can gain at least 2% advantage on interest rate. If the economy is on an upswing I'll sometimes delay refinancing, just because I know that in another year I'll get a better interest rate, so it's better to refinance once a bit later.
Also, if your credit rating is not quite where you'd like it to be, it's often better to save up $600k of cash and then repay one bond before taking out more. This can be enough (under some circumstances) to bump your credit rating an extra notch, so you get the new bonds at a lower rate.
In situations like this, I might have say $5 million worth of bonds at an average of 9%, but I have a good enough credit rating to get quite a few more bonds. Instead of just grabbing more, I'll repay as many as I can and then get one new bond. Then I'll repay another old one, then grab another new one. Keep doing this until all the old ones have been refinanced at the lowest possible rate, then keep grabbing new ones until the interest rate gets to your preferred limit.
Obviously this can't be done all the time. It depends where the game is at, but it's a handy trick to have up your sleeve.