Charles Schwab’s $26 billion acquisition of rival broker TD Ameritrade is set to close next week after the companies received final approval from regulators. The Federal Reserve signed off on the stock swap deal this week. The companies said the deal that was announced last November — not long after both brokers eliminated commissions on most stock trades — will close on Tuesday. Schwab and TD Ameritrade haven’t said how many jobs are expected to be eliminated after the merger, but significant cost cuts are expected. The companies say it will take 18 to 36 months to integrate the two companies.