Luke 6 reads as if he's talking about personal loans to your enemies. I'm not sure how a business loan to, say, Honda (since that's the example in the thread) is in the same category as a personal loan to your enemies. And to stay on the thread's topic, "lending" isn't what's happening in the stock market - the stock market is equity investment. You're taking an equity ownership stake in a business, not making a loan. In a loan, you specify the terms of the loan - the period of time, interest rate, and any collateral. In an equity investment, you're trying to turn a profit by providing a good or service to people who willingly exchange with you.
In fact, Jesus has positive things to say about investing with expecting return:
Matt
25:27 Then you should have deposited my money with the bankers, and on my return I would have received my money back with interest!
Lk
19:22 The king aid to him, ‘I will judge you by your own words, you wicked slave! So you knew, did you, that I was a severe man, withdrawing what I didn’t deposit and reaping what I didn’t sow?
19:23 Why then didn’t you put my money in the bank, so that when I returned I could have collected it with interest?’
This is an interesting verse too because it now only shows the wisdom of investing with an expected return, but it's also a form of lending. When you deposit money with bankers they lend it out on your behalf. What's more interesting in the parable is that God is the lender expecting a return on investment.
What differentiates this from Luke 6 is that Luke 6 seems to be talking about something specifically dealing with one's personal enemies. I think there is wisdom here as well in lending to one's enemies. Most people will see Luke 6's lending-to-enemies advice as a form of generosity, but it's really more shrewd. When you lend to someone, they become indebted to you and you become their creditor - you bear the risk. If they don't pay, their reputation suffers and you look generous for taking the risk. Lending to one's enemies potentially helps passivate their attitude towards you - you're now their creditor after all and it's their reputation that's at risk if they don't pay back their borrowings. You stand to turn your enemy into an ally and demonstrate your credibility and honesty in the eyes of others. Of course, if it's your enemy, you shouldn't expect them to pay you back - you should expect your enemy to try to take advantage of you (that's what enemies do). So in this particular example, I think Jesus is being more shrewd than he is saying to give away your money to your enemies as if you have a charity set just for them. He could have talked about charity here, but he chose to use the word for lending.
But the equity market is not a form of giving or lending. So your example is not comparable.
