After a rough August, Wall Street showed a solid run-up buoyed by global easing money policies and positive developments in U.S.-China trade relations that have instilled strong confidence in the stock market, returning investors’ risk appetite.While the rally has been broad based, small-cap stocks led the way higher this month with the Russell 2000 index gaining nearly 6.1%. In comparison, the S&P 500 and Mid Cap 400 indexes are up 3.8% and 5%, respectively. The outperformance was mainly driven by bargain hunting and rotation to the cheaper areas of the market (read: Why Small Cap ETFs Are Rising).The Fed slashed interest rates for the second time since the financial crisis by 25 bps to 1.75-2% in its policy meeting to sustain a decade-long economic expansion. Lower interest rates bode well for the pint-sized stocks, perking up economic activities and resulting in higher spending, thus boosting domestically focused companies.Additionally, the latest bout of upbeat data pointing to an increase in inflation, higher consumer and business confidence, retail sales, strong recovery in the U.S. housing market and solid manufacturing activity underscore the strength of the economy. As the pint-sized stocks are closely tied to the U.S. economy and do not have much exposure to the international market, these stocks generally outperform on improving American economic health.Given this, we highlight five small-cap ETFs and stocks that have outperformed in September. These could be excellent plays for investors should the same trends prevail.Best ETFsInvesco S&P SmallCap 600 Pure Value ETF RZVThis fund provides exposure to the pure-value segment of the small-cap market by tracking the S&P SmallCap 600 Pure Value Index (read: How to Play Stock Rotation With Value ETFs).Zacks ETF Rank: #3 (Hold)AUM: $182 millionExpense Ratio: 0.35%September Return: 10.1%Invesco S&P SmallCap 600 Revenue ETF RWJThis product offers exposure to securities of the S&P SmallCap 600 but is weighted by revenues instead of market capitalization.Zacks ETF Rank: #3AUM: $368.2 millionExpense Ratio: 0.39%September Return: 8.7%Invesco S&P SmallCap Value with Momentum ETF XSVMThis fund offers exposure to the companies having the highest "value scores" and "momentum scores" by tracking the S&P 600 High Momentum Value Index.Zacks ETF Rank: N/AAUM: $74.5 millionExpense Ratio: 0.39%September Return: 8.6%Invesco S&P SmallCap Materials ETF PSCMThis fund targets the materials sector offering exposure to companies that are principally engaged in producing raw materials, including paper or wood products, chemicals, construction materials, and mining and metals. It follows the S&P SmallCap 600 Capped Materials Index (read: Best Sector ETFs of September).Zacks ETF Rank: #3AUM: $15.6 millionExpense Ratio: 0.29%September Return: 8.5%Invesco S&P SmallCap High Dividend Low Volatility ETF XSHDThis ETF follows the S&P SmallCap 600 Low Volatility High Dividend Index, which is composed of 60 securities on the S&P SmallCap 600 Index that have historically provided high dividend yields with lower volatility over the past 12 months.Zacks ETF Rank: N/AAUM: $26.5 millionExpense Ratio: 0.30%September Return: 8.1%Best StocksLexicon Pharmaceuticals Inc. LXRXThis is a leader in defining the functions of genes for drug discovery using the large-scale knockout mouse technology.Zacks Rank: #3VGM Score: DMarket Cap: $365.04 millionSeptember Return: 160.2%Contango Oil & Gas Company MCFThis independent energy company is engaged in the acquisition, exploration, development, exploitation and production of crude oil and natural gas properties in the shallow waters of the Gulf of Mexico, and onshore properties in Texas and Wyoming in the United States (read: Profit From the Oil Rush With These ETFs).Zacks Rank: #3VGM Score: CMarket Cap: $85.35 millionSeptember Return: 148%Hovnanian Enterprises Inc HOVThis company designs, constructs, markets, and sells residential homes in the United States. It constructs single-family detached homes, attached townhomes and condominiums, urban infill, and active lifestyle homes.Zacks Rank: #3VGM Score: FMarket Cap: $109.53 millionSeptember Return: 142.4%Cesca Therapeutics Inc. KOOLThis company develops, commercializes, and markets a range of automated technologies for cell-based therapies in the United States, China, rest of Asia, Europe, and internationally. You can see the complete list of today’s Zacks #1 Rank stocks here.Zacks Rank: #1 (Strong Buy)VGM Score: DMarket Cap: $15.4 millionSeptember Return: 89%111 Inc. Sponsored ADR YIThis company operates an integrated online and offline platform in the healthcare market in the People's Republic of China.Zacks Rank: #3VGM Score: DMarket Cap: $391.41 millionSeptember Return: 78.4%Want key ETF info delivered straight to your inbox?Zacks’ free Fund Newsletter will brief you on top news and analysis, as well as top-performing ETFs, each week. Get it free >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Hovnanian Enterprises Inc (HOV): Free Stock Analysis Report Invesco S&P SmallCap 600 Revenue ETF (RWJ): ETF Research Reports Invesco S&P SmallCap Materials ETF (PSCM): ETF Research Reports Invesco S&P SmallCap 600 Pure Value ETF (RZV): ETF Research Reports Cesca Therapeutics Inc. (KOOL): Free Stock Analysis Report Lexicon Pharmaceuticals, Inc. (LXRX): Free Stock Analysis Report Contango Oil & Gas Company (MCF): Free Stock Analysis Report 111, Inc. Sponsored ADR (YI): Free Stock Analysis Report Invesco S&P SmallCap Value with Momentum ETF (XSVM): ETF Research Reports Invesco S&P SmallCap High Dividend Low Volatility ETF (XSHD): ETF Research Reports To read this article on Zacks.com click here. Zacks Investment Research Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report