NEW YORK (TheStreet) -- The month of September begins with more earnings from discount retailer Dollar Tree (DLTR - Get Report), video and image processing products maker Ambarella (AMBA - Get Report) and tax preparation company H&R Block (HRB - Get Report).

Among these companies, the one to focus on is Dollar Tree, which recently completed its merger with Family Dollar Stores. For the second quarter of fiscal 2015, analysts are forecasting the company to post profits of 62 cents a share on revenue of $3.04 billion. Last week, another discount retailer, Dollar General (DG - Get Report), posted its financial results that missed analysts' estimates on the top line.

Despite Dollar General's mixed earnings performance, TheStreet's Jim Cramer is optimistic about Dollar Tree. "I think that Dollar Tree is a better operator than Dollar General, and I think that the merger is brilliant," he said. "So, if Monday turns out to be a negative session, maybe put some on Dollar Tree because I think they're going to do better than Dollar General."

On the economics calendar, automakers will report August motor vehicle sales. They're expected to report a slight drop to annual rate of 17.3 million units from 17.4 million units in July. Despite the slight fall, numbers are overall expected to be strong. At 9:45 a.m. ET comes the PMI Manufacturing Index, followed by the ISM Manufacturing index at 10 a.m. ET These reports are both indicators of the economic health of the manufacturing sector.